KR20060113185A - Electron emission device and method for manufacturing the device - Google Patents

Abstract

An electron emission device and a method for manufacturing the same are provided to form an electron emission part by growing directly carbon-based materials on a catalytic layer. A cathode electrode(4), an insulating layer(6), and a gate electrode(8) are formed on a substrate(2). A plurality of openings are formed on the gate electrode and the insulating layer. A conductive layer is formed on an entire surface of a structure provided on the substrate. A catalytic layer(18) is formed on an electron emission unit region of the conductive layer. An electron emission unit(20) is formed by growing a carbon-based material on the catalytic layer. Carbon residues are removed from the remaining conductive layer except for the conductive layer under the catalytic layer.

Description

ELECTRON EMISSION DEVICE AND METHOD FOR MANUFACTURING THE DEVICE

1A to 1D are schematic diagrams at each step shown to explain a method of manufacturing an electron emitting device according to an embodiment of the present invention.

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron emitting device, and more particularly, to an electron emitting device and a method of manufacturing the electron emitting device, which form an electron emitting unit by growing a carbon-based material on a catalyst layer.

In general, the electron emission device may be classified into a method using a hot cathode and a cold cathode according to the type of the electron source.

Here, the electron emission device using the cold cathode is a field emitter array (FEA) type, surface conduction emission (SCE) type, metal-insulation layer-metal (insulation-type) metal (MIM) type and metal-insulation-semiconductor (MIS) type and the like are known.

Among them, the FEA type electron emission device uses a principle that electrons are easily emitted by an electric field in vacuum when a material having a low work function or a large aspect ratio is used as the electron source.

In the early FEA type electron emission device, a microtip structured electron emission part mainly made of molybdenum (Mo) or silicon (Si) was used. However, in order to manufacture an electron emitting device having an electron emitting unit having a microtip structure, a known semiconductor process must be used, and thus a manufacturing process is complicated, requires expensive equipment, and has a disadvantage in manufacturing a large screen device.

Accordingly, in recent years, in the field of FEA type electron emission devices, a technology for forming an electron emission unit using a carbon-based material that emits electrons well even under low voltage (approximately 10 to 50V) is being researched and developed.

Suitable carbon-based materials for the electron emitting portion include graphite, diamond-like carbon and carbon nanotubes, among which carbon nanotubes have a very small radius of curvature of about 100 kPa, with a low radius of 1 to 10 V / μm. It is expected to be an ideal electron emission material as electrons emit well in an electric field.

One method of forming an electron emission unit using the carbon-based material is a direct growth method. The direct growth method includes an electric discharge method, a laser deposition method, a plasma chemical vapor deposition method and a thermal chemical vapor deposition method. These methods mainly obtain a electron emission part by growing a carbon-based material on a catalyst layer.

Meanwhile, in the known FEA type electron emission device, a cathode electrode, an insulating layer, and a gate electrode are sequentially formed on a first substrate of two substrates constituting a vacuum container, and openings are formed in the gate electrode and the insulating layer, and the inside of the opening is formed. It has a structure in which an electron emission portion is formed on the cathode electrode. In addition, a structure in which an additional insulating layer is formed on the gate electrode and a focusing electrode is formed on the additional insulating layer is also widely used. Of course, the additional insulating layer and the focusing electrode are also formed with openings for electron beam passage.

In the above structure, the catalyst layer described above is required to form the electron emission unit using the direct growth method. To this end, before forming the insulating layer on the cathode electrode, a catalyst layer is formed on the cathode electrode, so that the catalyst layer is exposed by the opening of the gate electrode and the insulating layer. The carbon-based material is grown on the catalyst layer by using one of the aforementioned direct growth methods to form an electron emission portion.

However, when the carbon-based material is grown on the catalyst layer by using the above-described conventional method, carbon residues are formed on the undesired portions of the carbon-based material, that is, the opening surfaces of the two insulating layers and the side surfaces of the gate electrode and the focused electrode. It is present in a predetermined thickness. At this time, since the carbon residues are conductive, there is a fear that a short may be generated between the cathode electrode and the gate electrode, and between the gate electrode and the focusing electrode, and as a result, the withstand voltage characteristic of the electron emission device is degraded.

Therefore, the present invention is to solve the above problems, an object of the present invention is to prevent the remaining of carbon residues in the unintended site by the electron emission device and the method of manufacturing an electron emission device that can prevent the degradation of the voltage resistance To provide.

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

Forming a cathode electrode, an insulating layer and a gate electrode on the substrate, forming openings in the gate electrode and the insulating layer, forming a conductive layer over the entire surface of the structure provided in the substrate, and forming an electron emission region on the conductive layer. Forming an electron emission portion by forming a catalyst layer on the catalyst layer, directly growing a carbon-based material on the catalyst layer, and depositing a conductive layer of the remaining portions except the conductive layer under the catalyst layer on the conductive layer in the electron emission portion formation step. It provides a method for manufacturing an electron emitting device comprising the step of removing together with the carbon residues.

When the carbon-based material is grown, any one of an electric discharge method, a laser deposition method, a plasma chemical vapor deposition method, and a thermal chemical vapor deposition method is used.

When the catalyst layer is formed, iron (Fe), nickel (Ni), cobalt (Co), or an alloy thereof is deposited by any one of thermal evaporation and sputtering, and before the carbon-based material is grown on the catalyst layer, The catalyst layer is etched to form nanometer sized fine catalyst metal particles.

When the conductive layer is formed, the catalyst layer is formed of a conductive material etched by a different etching solution, and when the conductive layer is removed, the conductive layer is wet-etched using the conductive layer etchant. Preferably, when wet etching the conductive layer, the substrate is overetched to generate an undercut at the edge of the conductive layer.

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

An electron emitting portion comprising a first substrate and a second substrate disposed to face each other, a cathode electrode formed on the first substrate, a catalyst layer formed on the cathode electrode via the conductive layer, and carbon-based materials grown on the catalyst layer; And an electron emission device including an insulating layer and a gate electrode formed on the cathode electrode with respective openings for opening the electron emission part, a fluorescent layer formed on the second substrate, and an anode formed on one surface of the fluorescent layer. to provide.

The electron emission unit is made of any one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamond-like carbon, and C ₆₀ .

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

1A to 1D are schematic diagrams at each manufacturing step shown to explain a method for manufacturing an electron emitting device according to an embodiment of the present invention.

First, referring to FIG. 1A, a conductive film is formed on the first substrate 2 and patterned to form a striped cathode electrode 4, and an insulating material is formed on the entire first substrate 2 over the cathode electrode 4. The first insulating layer 6 is formed by thin film deposition or thick film printing. A conductive film is formed on the first insulating layer 6 and patterned to form a gate electrode 8 having a stripe shape orthogonal to the cathode electrode 6.

Subsequently, a thin film is deposited or thick-film printed on the first substrate 2 over the gate electrode 8 to form a second insulating layer 10, and a conductive material is coated on the second insulating layer 10 to focus. The electrode 12 is formed. In addition, the focus electrode 12, the second insulating layer 10, the gate electrode 8, and the first insulating layer 6 are sequentially etched to form the openings 14, so that the cathode electrode 4 on which the electron emission part is to be positioned. To expose some surface).

In this case, since the second insulating layer 10 and the focusing electrode 12 are optional additions, only the cathode electrode 4, the first insulating layer 6, and the gate electrode 8 are formed on the first substrate 2. You may.

Next, referring to FIG. 1B, the conductive material is coated on the entire surface of the structure provided on the first substrate 2 to form a conductive layer 16 to function as a sacrificial layer. The catalytic metal is again deposited on the surface of the conductive layer 16 by thermal evaporation or sputtering, and then patterned to form a catalyst layer 18 selectively at the electron emission region on the cathode electrode 4.

As the catalyst layer 18, iron (Fe), nickel (Ni), cobalt (Co) or an alloy of these three metals is preferable. The conductive layer 16 has a selective etching characteristic which is etched by a different etching solution from the catalyst layer 18, and a metal material having excellent conductivity, for example, molybdenum (Mo), aluminum (Al), silver (Ag), or the like is preferable. .

Subsequently, carbonaceous materials, in particular carbon nanotubes, are grown on the catalyst layer 18 as shown in FIG. 1C using any one of known electric discharge, laser deposition, plasma chemical vapor deposition, and thermal chemical vapor deposition. The discharge part 20 is formed. Carbon-based materials that can be synthesized using the direct growth method are not limited to carbon nanotubes, and include various carbon-based materials such as graphite, graphite nanofibers, diamond-like carbon, and C ₆₀ .

In particular, the direct growth method that can be effectively applied in the production method of this embodiment includes a plasma chemical vapor deposition method and a thermal chemical vapor deposition method. Plasma chemical vapor deposition has the advantage of synthesizing carbon-based materials at 550 ° C. or less, which is the deformation temperature of soda-lime glass, which is mainly used as the substrate for electron-emitting devices, and thermal chemical vapor deposition is suitable for synthesizing high-purity materials. The microstructure can be controlled, the device is simple and advantageous for mass synthesis.

In the case where the plasma chemical vapor deposition method and the thermal chemical vapor deposition method are applied, the catalyst layer 18 is etched using ammonia gas, hydrogen gas, or the like before the carbon-based material is synthesized on the catalyst layer 18. Forms fine catalytic metal particles of size. This is because carbon-based materials are synthesized on these fine catalytic metal particles.

The plasma chemical vapor deposition process is to generate a glow discharge within the chamber or reaction by direct current or high frequency power applied to the electrodes sikimyeo synthetic carbon-based materials from the fine metal particles in the catalyst layer, as the reaction gas C ₂ H _2, CH ₄ , C ₂ H ₄ , C ₂ H ₆ , or CO gas is used. In the thermal chemical vapor deposition method, a carbon-based material is synthesized from fine metal particles of a catalyst layer by installing a first substrate in a quartz reaction tube in which a heating coil is installed, and flowing a reaction gas into the quartz reaction tube.

As described above, the carbon emission material is synthesized from the catalyst layer 18 using the direct growth method to form the electron emission unit 20. Unexpected carbon residues 22 are produced in this process, which are deposited to an arbitrary thickness on the surface of the conductive layer 16 around the electron emission section 20.

Then, as shown in FIG. 1D, the conductive layer 16 in the remaining portions except for the conductive layer 16 ′ under the catalyst layer 18 is peeled off to remove the carbon residues 22 together with the conductive layer 16. do. When the conductive layer 16 is peeled off, a wet etching method in which the first substrate 2 is immersed in the conductive layer etchant and the conductive layer 16 is removed is preferable. In this process, the catalyst layer 18 serves as a mask layer so that the conductive layer 16 in the remaining portions except for the conductive layer 16 'under the catalyst layer 18 is removed.

In addition, when the conductive layer 16 is removed by the wet etching method, the conductive layer 16 is overetched to generate a so-called under-cut under the edge of the catalyst layer 18. In Fig. 1D, reference numeral 24 denotes an undercut generation site. This effectively removes carbon residues 22 around the electron emitter 20, and the remaining conductive layer 16 ′ only serves to electrically connect the cathode electrode 4 and the catalyst layer 18.

As described above, according to the manufacturing method of the present embodiment, the carbon residues 22 incidentally generated during the synthesis of the carbonaceous material on the catalyst layer 18 are removed together with the carbon residues 22 when the conductive layer 16 is peeled off. It is possible to prevent the deterioration of the breakdown voltage characteristic of the electron emitting device.

Hereinafter, a configuration of an electron emission device according to an exemplary embodiment of the present invention will be described with reference to FIG. 2.

Referring to FIG. 2, the electron emission device includes a first substrate 2 and a second substrate 26 disposed to face each other in parallel to each other with an internal space therebetween. Among the substrates, the first substrate 2 is provided with a configuration for emitting electrons completed according to the above-described manufacturing method, and the second substrate 26 is configured to emit visible light by electrons to perform arbitrary light emission or display. This is provided.

First, the cathode electrodes 4 and the gate electrodes 8 are formed on the first substrate 2 in a stripe pattern along a direction orthogonal to each other with the first insulating layer 6 interposed therebetween. In the present exemplary embodiment, when the intersection area between the cathode electrode 4 and the gate electrode 8 is defined as the pixel area, one or more electron emission parts 20 are formed in each pixel area over the cathode electrode 4.

The electron emission unit 20 is made of a carbon-based material, and the carbon-based material used as the electron emission unit 20 includes carbon nanotubes, graphite, graphite nanofibers, diamond-like carbon, and C ₆₀ .

The electron emission part 20 is formed on the catalyst layer 18, and a conductive layer 16 ′ is disposed between the cathode electrode 4 and the catalyst layer 18 to electrically connect them. The conductive layer 16 ′ has an undercut formed at an edge thereof to have a width smaller than that of the catalyst layer 18, and has a selective etching characteristic to be etched by a different etchant from the catalyst layer 18. The catalyst layer 18 is preferably iron (Fe), nickel (Ni), cobalt (Co) or an alloy of these three metals, and the conductive layer 16 'is made of molybdenum (Mo), aluminum (Al), or silver ( Ag).

The second insulating layer 10 and the focusing electrode 12 are formed on the gate electrode 8 and the first insulating layer 6. The focusing electrode 12, the second insulating layer 10, the gate electrode 8, and the first insulating layer 6 may have an opening 14 for exposing the electron emission part 20 on the first substrate 2. To form. In the drawing, for example, the opening 14b of the focusing electrode 12 and the second insulating layer 10 surrounds the pair of openings 14a provided in the gate electrode 8 and the first insulating layer 6. Shown.

In addition, a fluorescent layer 28 and a black layer 30 are formed on one surface of the second substrate 26 facing the first substrate 2, and a metal such as aluminum is disposed on the fluorescent layer 28 and the black layer 30. An anode electrode 32 made of a film is formed. The anode electrode 32 receives a voltage necessary for accelerating the electron beam from the outside, and reflects the visible light emitted toward the first substrate 2 of the visible light emitted from the fluorescent layer 28 toward the second substrate 26 to display the screen. It increases the brightness.

The anode electrode may be made of a transparent conductive film such as indium tin oxide (ITO) instead of a metal film. In this case, the anode electrode may be positioned on one surface of the fluorescent layer facing the second substrate and the black layer, and may be formed in plural in a predetermined pattern.

The first substrate 2 and the second substrate 26 described above are integrally bonded to each other by a sealing material such as glass frit in a state where spacers 34 are disposed therebetween, By exhausting and maintaining in a vacuum state, an electron emission element is comprised. In this case, the spacers 34 are disposed corresponding to the non-light emitting region where the black layer 30 is located.

The electron-emitting device of the above configuration is driven by supplying a predetermined voltage to the cathode electrode 4, the gate electrode 8, the focusing electrode 12 and the anode electrode 32 from the outside, for example the cathode electrode 4 and A scan voltage pulse is applied to one of the gate electrodes 8, a data voltage pulse is applied to the other electrode, a negative DC voltage of several to several tens of volts is applied to the focusing electrode 12, and the anode electrode 32 ) Is applied a positive DC voltage of several hundred to several thousand volts.

Therefore, in the pixel in which the voltage difference between the cathode electrode 4 and the gate electrode 8 is greater than or equal to the threshold, an electric field is formed around the electron emission part 20 and electrons are emitted therefrom, and the emitted electrons pass through the focusing electrode 12. While being focused, it is attracted by the high voltage applied to the anode electrode 32 and collides with the corresponding fluorescent layer 28 to emit light.

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, according to the present invention, when the carbon-based material is formed on the catalyst layer to form the electron emission portion, even though carbon residues are generated around the electron emission portion, the carbon residues can be effectively removed in the process of removing the conductive layer later. have. Therefore, the electron emission device according to the present invention can secure excellent withstand voltage characteristics between the cathode electrode and the gate electrode, and between the gate electrode and the focusing electrode.

Claims (13)

(a) forming a cathode electrode, an insulating layer, and a gate electrode on the substrate, and forming openings in the gate electrode and the insulating layer; (b) forming a conductive layer over the entire surface of the structure provided in the substrate; (c) forming a catalyst layer at a location where an electron emission region is formed on the conductive layer; (d) directly growing a carbon-based material on the catalyst layer to form an electron emission unit; And (e) removing the conductive layer of the remaining portions except for the conductive layer under the catalyst layer together with the carbon residues deposited on the conductive layer in step (d). Method of manufacturing an electron emitting device comprising a. The method of claim 1, A method of manufacturing an electron emitting device using any one of an electric discharge method, a laser deposition method, a plasma chemical vapor deposition method and a thermal chemical vapor deposition method when growing the carbonaceous material. The method of claim 1, When the catalyst layer is formed, iron (Fe), nickel (Ni), cobalt (Co), or an alloy thereof is deposited by any one of thermal evaporation and sputtering, Before growing the carbonaceous material on the catalyst layer, etching the catalyst layer to form nanometer-sized fine catalyst metal particles. The method of claim 1, When the conductive layer is formed, a method of manufacturing an electron emission device is formed of a conductive material that is etched by a different etchant from the catalyst layer. The method of claim 4, wherein Molybdenum (Mo), aluminum (Al), or silver (Ag) is deposited when the conductive layer is formed. The method of claim 4, wherein When the conductive layer is removed, a method of manufacturing an electron emission device wet etching the conductive layer using a conductive layer etchant. The method of claim 6, When wet etching the conductive layer, a method of manufacturing an electron emission device to generate an under-cut to the edge of the conductive layer by over-etching. The method according to any one of claims 1 to 7, Between steps (a) and (b), Forming an additional insulating layer and a focusing electrode over the gate electrode and the insulating layer, and forming openings in the focusing electrode and the additional insulating layer. A first substrate and a second substrate disposed to face each other; A cathode electrode formed on the first substrate; A catalyst layer formed on the cathode electrode via a conductive layer; An electron emission unit made of carbon-based materials grown on the catalyst layer; An insulating layer and a gate electrode formed over said cathode electrode with respective openings for opening said electron emission portion; A fluorescent layer formed on the second substrate; And An anode formed on one surface of the fluorescent layer Electron emitting device comprising a. The method of claim 9, The electron emitting device of claim 1, wherein the electron emission unit is made of one selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamond-like carbon, and C ₆₀ . The method of claim 9, The conductive layer has an undercut formed on the edge has a smaller width than the catalyst layer is formed. The method of claim 9, The catalyst layer is made of any one material selected from the group consisting of iron (Fe), nickel (Ni), cobalt (Co) and alloys thereof, And the conductive layer is made of any one material selected from the group consisting of molybdenum (Mo), aluminum (Al), and silver (Ag). The method of claim 9, And an additional insulating layer and a focusing electrode formed on the insulating layer and the gate electrode.

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