KR20080023957A - Electron emission device and method of manufacturing the same - Google Patents

Abstract

An electron emission device and a manufacturing method of the same are provided to separate electron emission materials from each other on a surface of an electron emission source by growing a carbon nano-tube at a catalytic metal layer having an exposed part. A cathode electrode(120) is formed on an upper surface of a base substrate(110). A gate electrode(140) is electrically isolated from the cathode electrode. A first insulator layer(130) is arranged between the cathode electrode and the gate electrode in order to isolate electrically the cathode electrode and the gate electrode. An electron emission source hole(131) is formed at the first insulator layer and the gate electrode in order to expose the cathode electrode. An electron emission source(250) is arranged within the electron emission source hole and is formed by using an electron emission material(252), a catalytic metal layer(251), and a tungsten pattern layer(253).

Description

Electron emission device and method of manufacturing the same

1 is a partial cutaway perspective view schematically showing a configuration of an electron emitting device according to Embodiment 1 of the present invention.

2 is a cross-sectional view taken along the line II-II of FIG.

3 is an enlarged view of section III of FIG. 2;

4 to 9 are views sequentially showing a method of manufacturing an electron emitting device according to the present invention.

Fig. 10 is a partially cutaway perspective view schematically showing the configuration of an electron emitting device according to a second embodiment of the present invention.

FIG. 11 is a cross-sectional view taken along the line XI-XI of FIG. 10.

<Explanation of symbols for the main parts of the drawings>

60: spacer 70: phosphor layer

80: anode electrode 90: front substrate

100: electron emission display device 101, 201: electron emission device

110: base substrate 120: cathode electrode

130: first insulator layer 131: electron emission source hole

135: second insulator layer 140: gate electrode

145: focusing electrode 250: electron emission source

251: catalytic metal layer 252: electron emitting material

253: tungsten pattern layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron emission device and a method for manufacturing the same, and more particularly, to an electron emission source made of a carbon-based material or a nanomaterial, wherein a carbon-based material or nanomaterial is formed on the surface of the electron emission source. The present invention relates to an electron-emitting device and a method of manufacturing the same, which are present on the surface and are raised, and have an electron emission source arranged uniformly.

In general, an electron emission device includes a method using a hot cathode and a cold cathode as an electron emission source. Examples of electron emission devices using a cold cathode include field emission device (FED) type, surface conduction emitter (SCE) type, metal insulator metal (MIM) type, metal insulator semiconductor (MIS) type, and ballistic electron surface emitting (BSE) type. ) And the like are known.

The FED type uses a principle that electrons are easily released due to electric field difference in vacuum when a material having a low work function or a high beta function is used as the electron emission source. Molybdenum (Mo), silicon (Si), etc. A tip structure with sharp tip, carbon-based materials such as graphite and DLC (Diamond Like Carbon), and nano-materials such as nanotubes and nanowires. Has been developed to apply an electron emission source.

The SCE type is a device in which an electron emission source is formed by providing a conductive thin film between the first electrode and the second electrode disposed to face each other on a base substrate and providing a micro crack in the conductive thin film. The device uses a principle that electrons are emitted from an electron emission source that is a micro crack by applying a voltage to the electrodes to flow a current to the surface of the conductive thin film.

The MIM type and the MIS type electron emission devices each form an electron emission source having a metal-dielectric layer-metal (MIM) and metal-dielectric layer-semiconductor (MIS) structure, and are disposed between two metals or metals with a dielectric layer interposed therebetween. When a voltage is applied between semiconductors, a device using the principle of emitting electrons is moved and accelerated from a metal or semiconductor having a high electron potential toward a metal having a low electron potential.

The BSE type uses the principle that electrons travel without scattering when the size of the semiconductor is reduced to a dimension area smaller than the average free stroke of the electrons in the semiconductor, thereby forming an electron supply layer made of a metal or a semiconductor on an ohmic electrode. And an insulator layer and a metal thin film formed on the electron supply layer to emit electrons by applying power to the ohmic electrode and the metal thin film.

Recently, in the FED type electron emission device, a needle material composed mainly of a carbon-based material is used as the electron emission source as mentioned above. When manufacturing an electron emission source including a carbon-based material by using a known method, the carbon-based material or nanomaterial constituting the electron emission source is often buried inside without being exposed to the surface, and thus is effectively utilized as an electron emission source. There were many cases that could not be.

In addition, even when a portion of the carbon-based material or nanomaterials protrudes from the surface, the ends of which are known to generate most of the electrons are directed to the left and right sides instead of the top, so that the electrons are unevenly emitted in many cases.

In addition, when the ends of the electron-emitting materials are not separated from each other by a certain distance, the electron-emitting materials located close together act as one electron-emitting material having a large diameter, so that the electron emission characteristics are excellent according to the large shape of the device. There was a problem in which a screen effect, which became difficult, appeared.

As a result of these problems, there is a problem that the electron emission characteristics are degraded and the screen is uneven, and there is a great need to find a way to improve them.

The present invention is to overcome the above-mentioned conventional problems, an object of the present invention is to provide an electron emitting device and a method of manufacturing the same that can avoid the screen effect in the electron emission source and the electron emission efficiency is improved.

The object of the present invention as described above,

A base substrate;

A cathode electrode disposed on the base substrate;

A gate electrode disposed to be electrically insulated from the cathode electrode;

A first insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrode and the gate electrode; And

An electron emission hole is formed in the first insulator layer and the gate electrode to expose the cathode electrode, is disposed in the electron emission hole, and has an electron emission material, a catalyst metal layer, and a tungsten pattern layer; It is achieved by providing an electron emitting device comprising a circle.

Here, the catalyst metal layer is disposed to be electrically connected to the cathode electrode,

The tungsten pattern layer is disposed above the catalyst metal layer to partially expose the catalyst metal layer,

Preferably, the electron emission material is disposed so that the catalyst metal layer is electrically connected to the catalyst metal layer at a portion exposed by the tungsten pattern layer.

Here, the catalyst metal layer preferably includes Fe, Co, Ni, or an alloy of a metal selected from these.

Here, the thickness of the catalyst metal layer is preferably in the range of 0.5nm to 100nm.

Here, the tungsten pattern layer may be an irregular crack formed in the tungsten layer of a predetermined thickness, or a plurality of holes of a predetermined diameter may be formed in the tungsten layer of a predetermined thickness.

Here, the thickness of the tungsten pattern layer is preferably in the range of 0.5㎛ 10㎛.

Here, it is preferable to further include a focusing electrode disposed in an electrically insulated state from the gate electrode, and a second insulator layer disposed between the focusing electrode and the gate electrode.

Here, the cathode electrode and the gate electrode is preferably formed to cross each other with the first insulator layer therebetween.

In addition, the object of the present invention as described above,

In the method of manufacturing an electron emitting device,

Forming a catalytic metal layer (a);

(B) forming a tungsten pattern layer on the catalyst metal layer so that the catalyst metal layer is partially exposed; And

It is achieved by providing a method of manufacturing an electron emitting device comprising the step (c) of growing an electron emitting material from a catalytic metal layer partially exposed by the tungsten pattern layer.

Here, the step (a),

Preparing a base substrate;

Forming a cathode electrode extending in one direction on the base substrate;

Forming a first insulator layer on the base substrate to cover the cathode electrode;

Forming a gate electrode on the first insulator layer in a direction crossing the cathode electrode;

Forming an electron emission source hole on the first insulator layer and the gate electrode to expose the cathode electrode; And

Forming a catalytic metal layer on the exposed cathode electrode.

Or wherein, in step (a),

Preparing a base substrate;

Forming a cathode electrode extending in one direction on the base substrate;

Forming a first insulator layer on the base substrate to cover the cathode electrode;

Forming a gate electrode on the first insulator layer in a direction crossing the cathode electrode;

Forming a second insulator layer to cover the cathode electrode;

Forming the focusing electrode on the second insulator layer;

Forming an electron emission source hole on the first insulator layer, the gate electrode, the second insulator layer, and the focusing electrode to expose the cathode electrode; And

Forming a catalytic metal layer on the exposed cathode electrode.

Here, the step (b),

Through a photolithography process, a tungsten pattern layer having a predetermined thickness in which a plurality of holes of a predetermined size are formed is formed, or a tungsten layer is formed on the catalyst metal layer by CVD or the like, and a nitrogen atmosphere at a temperature of 200 ° C. or higher and 600 ° C. or lower. By forming the cracks in the tungsten layer may be to form a tungsten pattern layer to partially expose the catalyst metal layer.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

FIG. 1 is a partial cutaway perspective view schematically showing the configuration of an electron emitting device according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, and FIG. An enlarged view of section III of FIG. 2 is shown.

As shown in FIGS. 1 to 3, the electron emission device 101 according to the first embodiment of the present invention may include a base substrate 110, a cathode electrode 120, a gate electrode 140, and a first insulator layer. 130 and an electron emission source 250.

The base substrate 110 is a plate-like member having a predetermined thickness, and may include quartz glass, glass containing a small amount of impurities such as Na, glass, a SiO ₂ coated glass substrate, aluminum oxide, or a ceramic substrate. . In addition, when implementing a flexible display apparatus, a flexible material may be used.

The cathode electrode 120 is disposed to extend in one direction on the base substrate 110 and may be made of a conventional electrically conductive material. For example, it may be made of a metal such as Al, Ti, Cr, Ni, Au, Ag, Mo, W, Pt, Cu, Pd or an alloy thereof. Alternatively, it may be made of a printed conductor composed of metal or metal oxide and glass such as Pd, Ag, RuO ₂ , Pd-Ag and the like. Alternatively, it may be made of a transparent conductor such as ITO, In ₂ O ₃ or SnO ₂ , or a semiconductor material such as polysilicon.

The gate electrode 140 may be disposed with the cathode electrode 120 and the insulator layer 130 interposed therebetween, and may be made of a conventional electrically conductive material like the cathode electrode 120.

The insulator layer 130 is disposed between the gate electrode 140 and the cathode electrode 120 to insulate the cathode electrode 120 and the gate electrode 140 to generate a short between the two electrodes. prevent.

The electron emission source 250 is disposed to be energized with the cathode electrode 120, and has a lower height than the gate electrode 140. The electron emission source 250 includes an electron emission material 252, a catalyst metal layer 251, and a tungsten pattern layer 253. The electron emission material 252 may be a carbon nanotube (CNT) grown from the catalyst metal layer. Carbon nanotubes have a small work function and a large beta function, and have excellent electron emission characteristics. In addition, as the electron emission material, carbon-based materials such as graphite, diamond and diamond-like carbon, and nanomaterials such as nanowires and nanorods may be used.

The catalyst metal layer 251 is preferably made of Fe, Co, Ni, or an alloy of metals selected from these, but is not limited thereto. The catalyst metal layer 251 may be made of a metal salt including a transition metal. The catalyst metal layer 251 preferably has a thickness in the range of 0.5 nm to 100 nm.

The tungsten pattern layer partially exposes the catalyst metal layer in a pattern in which predetermined holes are formed or in a pattern in which cracks are formed. The thickness of the tungsten pattern layer is in the range of 0.5 µm to 10 µm, preferably about 0.5 µm. Carbon nanotubes are grown on the catalytic metal layer partially exposed by the tungsten pattern layer to function as an electron emission material.

The electron emission device 101 having the above-described configuration applies a negative voltage to the cathode electrode and a positive voltage to the gate electrode to between the cathode electrode 120 and the gate electrode 140. The electrons may be emitted from the electron emission source 250 by an electric field formed in the electron emission source 250. Of course, electron emission is possible even when the voltage applied to the cathode electrode is a positive voltage and the voltage applied to the gate electrode is a higher positive voltage.

In addition, the electron emission device 101 described above may be used for the electron emission display device 100 that generates visible light to implement an image. In order to configure the electron emission display device, a phosphor should be disposed in front of the electron emission source of the electron emission device according to the present invention. To this end, it further comprises a front panel 102 disposed in parallel with the base substrate 110 of the electron emission element 101, the front panel 102 is on the front substrate 90, the front substrate 90 It may be configured to further include an anode electrode 80 and a phosphor layer 70 provided on the anode electrode (80) installed in the.

The front substrate 90 is a plate-like member having a predetermined thickness like the base substrate 110, and may be made of the same material as the base substrate 110. The anode electrode 80 is made of a conventional electrically conductive material similarly to the cathode electrode 120 and the gate electrode 140. The phosphor layer 70 is made of a CL (Cathode Luminescence) phosphor that is excited by the accelerated electrons to generate visible light. Phosphors that can be used in the phosphor layer 70 include, for example, red phosphors including SrTiO ₃ : Pr, Y ₂ O ₃ : Eu, Y ₂ O ₃ S: Eu, or Zn (Ga, Al ) ₂ O ₄ : Mn, Y ₃ (Al, Ga) ₅ O ₁₂ : Tb, Y ₂ SiO ₅ : Phosphor for green light including Tb, ZnS: Cu, Al, or Y ₂ SiO ₅ : Ce, ZnGa ₂ There is a blue light phosphor containing O ₄ , ZnS: Ag, Cl and the like. Of course, it is not limited to the phosphors mentioned herein.

In addition, the cathode electrode 120 and the gate electrode 140 may be disposed to cross each other in order to implement an image instead of simply generating visible light as a lamp.

In addition, electron emission source holes 131 are formed in regions where the gate electrodes 140 and the cathode electrode 120 cross each other, and the electron emission source 250 is disposed therein.

The electron emission device 100 including the base substrate 110 and the front panel 102 including the front substrate 90 face each other while maintaining a predetermined distance therebetween to form a light emitting space, and the electron emission device Spacers 60 are disposed to maintain a gap between the 100 and the front panel 102. The spacer 60 may be made of an insulating material.

In addition, in order to maintain the vacuum inside, the circumference of the space formed by the electron emission element 100 and the front panel 102 is sealed, and the air inside is exhausted. The electron emission display device having such a configuration operates as follows.

Electrons are emitted from the electron emission source 250 installed on the cathode electrode 120 by applying a negative voltage to the cathode electrode 120 and applying a positive voltage to the gate electrode 140 for electron emission. To be possible. In addition, a strong (+) voltage is applied to the anode electrode 80 to accelerate electrons emitted toward the anode electrode 80. When the voltage is applied in this way, electrons are emitted from the needle-like materials constituting the electron emission source 250, proceed toward the gate electrode 140, and are accelerated toward the anode electrode 80. Electrons accelerated toward the anode electrode 80 impinge on the phosphor layer 70 positioned on the anode electrode 80 to excite the phosphor layer to generate visible light.

Hereinafter, a method of manufacturing an electron emitting device according to the present invention will be described.

4 to 9 are views sequentially showing a method of manufacturing an electron emitting device according to the present invention.

First, as shown in FIG. 4, materials for forming the base substrate 110, the cathode electrode 120, the first insulator layer 130, and the gate electrode 140 are sequentially stacked to have a predetermined thickness. Lamination is preferably performed by a process such as screen printing.

Next, a mask pattern (not shown) is formed on the upper surface of the gate electrode 140 with a predetermined thickness. The formation of the mask pattern is to form an electron emission hole, and is performed by a photolithography process using a photoresist (PR) and using UV or E-beam.

Next, as illustrated in FIG. 5, the gate electrode 140 and the first insulator layer 130 are etched using the mask pattern to form the electron emission source holes 131. The etching process may be performed by a wet etching method using an etchant, a dry etching method using a corrosive gas, or a micro machining method using an ion beam, such as an ion beam, depending on the material and thickness of the gate electrode 140 and the insulator layer 130. have.

Then, a photoresist layer is formed to cover the gate electrode and insulator layer, and only the portion where the electron emission source is to be formed is exposed.

Then, as shown in FIG. 6, the catalyst metal layer is formed to a predetermined thickness at the portion where the electron emission source is to be formed.

Next, a tungsten layer is formed on the catalyst metal layer as shown in FIG. 7, and the tungsten layer is then processed as shown in FIG. 8 to form a tungsten pattern layer. The tungsten pattern layer may be formed in the following manner. One method is to form a photoresist layer on the catalyst metal layer and leave the photoresist layer only at the position where the carbon nanotubes are to be grown on the photoresist layer through the photolithography process. How to form. After the deposition of tungsten is completed, the photoresist may be removed to form a tungsten pattern layer in which the catalyst metal layer is exposed only at the position where the carbon nanotubes are to be formed.

Another method is to form a tungsten layer with a thickness of about 0.5 [mu] m by CVD or the like, and maintain a nitrogen atmosphere at a temperature of about 200 [deg.] C. to about 600 [deg.] C. or less, preferably about 300 [deg.] C. There is a method of obtaining a desired tungsten pattern layer while cracks are formed.

After the tungsten pattern layer is formed, carbon nanotubes are grown by chemical vapor deposition (CVD) direct growth method from the catalyst metal layers exposed by holes or cracks formed in the tungsten pattern layer (FIG. 9). As the carbon nanotubes are grown in the partially exposed catalytic metal layer, the carbon nanotubes are densely present, and the screen effect can be avoided. As a result, the electron emission efficiency of the electron emission device can be improved.

On the other hand, the tungsten pattern layer may be removed by using hydrogen peroxide or ammonia water when the growth of the carbon nanotubes, which are electron emission materials, is completed.

FIG. 10 is a perspective view showing the configuration of an electron emission device according to Embodiment 2 of the present invention, and FIG. 11 is a partial cross-sectional view taken along the line XI-XI of FIG. 10.

As shown in FIGS. 10 and 11, the electron emission device 201 of Embodiment 2 is disposed above the second insulator layer 135 and the second insulator layer 135 covering the upper side of the gate electrode 140. The focusing electrode 145 is further included. By further including the focusing electrode 145, electrons emitted from the electron emission source 250 may be prevented from being focused toward the phosphor layer and dispersed in left and right directions. Also in this embodiment, the carbon nanotubes included in the electron emission source and functioning as the electron emission material may be grown from the catalyst metal layer partially exposed by the tungsten pattern layer. Accordingly, the carbon nanotubes are not crowded with each other and end portions thereof are separated, thereby avoiding the screen effect and increasing the electron emission efficiency.

According to the electron emitting device and the method of manufacturing the same according to the present invention described above, the carbon nanotubes included in the electron emitting device are grown in a partially exposed catalytic metal layer, whereby the electron emitting materials are separated from each other on the surface of the electron emitting source. Is placed. Accordingly, screen effects that may occur when the carbon nanotubes are densely grown are avoided. In particular, in the method of manufacturing an electron emitting device according to the present invention, there is an advantage in that an electron emitting material can be easily formed in an electron emitting device in which an electron emission source hole of 6 μm or more is formed.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (14)

A base substrate; A cathode electrode disposed on the base substrate; A gate electrode disposed to be electrically insulated from the cathode electrode; A first insulator layer disposed between the cathode electrode and the gate electrode to insulate the cathode electrode and the gate electrode; And An electron emission hole is formed in the first insulator layer and the gate electrode to expose the cathode electrode, is disposed in the electron emission hole, and has an electron emission material, a catalyst metal layer, and a tungsten pattern layer; An electron emitting device comprising a circle. The method of claim 1, The catalyst metal layer is disposed to be electrically connected to the cathode electrode, The tungsten pattern layer is disposed above the catalyst metal layer to partially expose the catalyst metal layer, And the electron-emitting material is disposed so as to be electrically connected to the catalyst metal layer in a portion where the catalyst metal layer is exposed by the tungsten pattern layer. The method of claim 1, The catalyst metal layer is an electron emission device characterized in that it comprises Fe, Co, Ni, or an alloy of a metal selected from these. The method of claim 1, The thickness of the catalyst metal layer is an electron emitting device, characterized in that in the range of 0.50nm to 100nm. The method of claim 1, The tungsten pattern layer is an electron emission device, characterized in that irregular cracks are formed in the tungsten layer of a predetermined thickness. The method of claim 1, The tungsten pattern layer is an electron emission device, characterized in that a plurality of holes of a predetermined diameter are formed in a tungsten layer of a predetermined thickness. The method of claim 1, The thickness of the tungsten pattern layer is an electron emission device, characterized in that in the range of 0.5㎛ to 10㎛. The method of claim 1, And a second insulator layer disposed between the focusing electrode and the gate electrode, wherein the focusing electrode is electrically insulated from the gate electrode. The method of claim 1, And the cathode electrode and the gate electrode cross each other with the first insulator layer interposed therebetween. In the method of manufacturing an electron emitting device, Forming a catalytic metal layer (a); (B) forming a tungsten pattern layer on the catalyst metal layer so that the catalyst metal layer is partially exposed; And (C) growing an electron emission material from the catalyst metal layer partially exposed by the tungsten pattern layer. The method of claim 10, Step (a) is, Preparing a base substrate; Forming a cathode electrode extending in one direction on the base substrate; Forming a first insulator layer on the base substrate to cover the cathode electrode; Forming a gate electrode on the first insulator layer in a direction crossing the cathode electrode; Forming an electron emission source hole on the first insulator layer and the gate electrode to expose the cathode electrode; And And forming a catalyst metal layer on the exposed cathode electrode. The method of claim 10, Step (a) is, Preparing a base substrate; Forming a cathode electrode extending in one direction on the base substrate; Forming a first insulator layer on the base substrate to cover the cathode electrode; Forming a gate electrode on the first insulator layer in a direction crossing the cathode electrode; Forming a second insulator layer to cover the cathode electrode; Forming the focusing electrode on the second insulator layer; Forming an electron emission source hole on the first insulator layer, the gate electrode, the second insulator layer, and the focusing electrode to expose the cathode electrode; And And forming a catalyst metal layer on the exposed cathode electrode. The method of claim 10, Step (b) is, And a tungsten pattern layer having a predetermined thickness in which a plurality of holes of a predetermined size are formed through a photolithography process. The method of claim 10, Step (b) is, Forming a tungsten layer on top of the catalyst metal layer by a CVD process, by forming a crack in the tungsten layer by maintaining a nitrogen atmosphere at a temperature of 200 ℃ to 600 ℃ to form a tungsten pattern layer to partially expose the catalyst metal layer Method for producing an electron emitting device, characterized in that.

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