KR20080013299A - Electron emission device - Google Patents

Abstract

An electron emission device is provided to enhance adhesive strength between a main electrode and an auxiliary electrode by forming sequentially an adhesive layer and the auxiliary electrode on the main electrode. A cathode electrode(14) is formed on a substrate(10). An electron emission unit(20) is electrically connected to the cathode electrode. The cathode electrode includes a main electrode(141), an auxiliary electrode(142), and an adhesive layer(143). The main electrode is extended along a cross direction of the substrate. The auxiliary electrode is formed on the main electrode. The adhesive layer is formed between the main electrode and the auxiliary electrode. The adhesive layer has a thickness of 500 to 800 angstrom. The adhesive layer includes Cr or Ti.

Description

Electron Emission Device {ELECTRON EMISSION DEVICE}

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

2 is a partial cross-sectional view of an electron emission display using an electron emission device according to an embodiment of the present invention.

TECHNICAL FIELD The present invention relates to an electron emitting device, and more particularly, to an electron emitting device having an auxiliary electrode for lowering a resistance value of a cathode electrode.

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

The electron emission device using the cold cathode may include a field emission array (FEA) type, a surface conduction emission type (SCE) type, and a metal-insulating layer-metal type. Metal (MIM) type and Metal-Insulator-Semiconductor (MIS) type are known.

The field emission array (FEA) type electron emission device includes an electron emission portion and a cathode and a gate electrode as a driving electrode, and a material having a low work function or a high aspect ratio as a constituent material of the electron emission portion, For example, using a carbon-based material or a nanometer sized material uses the principle that electrons are easily released by an electric field in a vacuum.

Electron emitting elements are arranged in an array on the first substrate to form an electron emitting device together with the first substrate, which in combination with the second substrate and the light emitting unit provided on the second substrate constitutes an electron emitting display.

A typical field emission array (FEA) type electron emission device has cathode electrodes, insulating layers and gate electrodes sequentially formed on a substrate, and openings are formed in the gate electrodes and the insulating layer to expose a portion of the surface of the cathode electrode, The electron emission portion is disposed on the cathode electrodes inside the opening.

When the conventional electron emission unit is manufactured by a known screen printing method, the substrate is subjected to a back exposure process in which ultraviolet rays are irradiated from the rear surface of the substrate. For this purpose, the substrate is prepared as a transparent substrate, and the cathode electrode is made of a transparent material, for example, indium tin. It is formed of oxide (Indium Tin Oxide; ITO).

In this case, since indium tin oxide having a high resistance value requires a high driving voltage, conventionally, an auxiliary electrode is formed of a material having a lower resistance value on the indium tin oxide to lower the resistance value of the cathode electrode.

However, indium tin oxide causes various problems in forming an auxiliary electrode because of poor adhesion with low resistance metals. For example, the application of aluminum (Al) as an auxiliary electrode causes aluminum to cause indium tin oxide and galvanic corrosion.In the case of the silver (Ag) auxiliary electrode, the contact area with the main electrode is overetched when the cathode is etched. The step coverage of the electrode is poor.

For this reason, in the past, although the effect of lowering the resistance value of the cathode is small, the auxiliary electrode is formed of a metal having excellent bonding strength with indium tin oxide, for example, chromium (Cr). Can't expect it.

Accordingly, an object of the present invention is to provide an electron emission device capable of optimally securing a resistance value of a cathode by forming an auxiliary electrode.

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

A substrate, a cathode electrode formed on the substrate, an electron emission portion electrically connected to the cathode electrode, the cathode electrode extending in one direction of the substrate, an auxiliary electrode formed on the main electrode, between the main electrode and the auxiliary electrode It provides an electron emission device comprising an adhesive layer formed on.

The adhesive layer may be formed to a thickness of 500 to 800Å, and may include chromium (Cr) or titanium (Ti).

The auxiliary electrode is made of a material having a lower resistance value than the main electrode and the adhesive layer, and may be formed of silver (Ag) or aluminum (Al).

In addition, one auxiliary electrode and one adhesive layer may be formed on each of left and right sides of the electron emission unit.

The main electrode may be made of indium tin oxide (ITO), and the electron emission part may be formed on the main electrode by an exposure process by ultraviolet rays irradiated from the rear surface of the substrate.

The electron emitting device may include a gate electrode positioned insulated from the cathode electrode.

In addition, the electron emission unit may include a material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ), silicon nanowires, and combinations thereof.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 and 2 are partially exploded perspective and partial cross-sectional views of an electron emission display device using an electron emission device according to an embodiment of the present invention, respectively.

Referring to the drawings, the electron emission display device includes a first substrate 10 and a second substrate 12 which are disposed in parallel to each other at predetermined intervals. Sealing members (not shown) are disposed at the edges of the first substrate 10 and the second substrate 12 to bond the two substrates 10 and 12, thereby providing the first substrate 10 and the second substrate. 12 constitutes a container having an inner space. The vessel consists of a vacuum vessel whose internal space is evacuated to a vacuum of approximately 10 ^-6 Torr.

An electron emission unit 100 including field emission array (FEA) type electron emission devices is provided on one surface of the first substrate 10 facing the second substrate 12, and is provided on the first substrate 10. The light emitting unit 110 is provided on one surface of the opposing second substrate 12.

First, the electron emission unit 100 will be described. On the first substrate 10, the cathode electrodes 14, which are the first electrodes, form one direction (the x-axis direction in the drawing) of the first substrate 10. Accordingly, the first insulating layer 16 is formed on the entirety of the first substrate 10 while covering the cathode electrodes 14. Gate electrodes 18 serving as second electrodes are formed on the first insulating layer 16 in a stripe pattern along a direction orthogonal to the cathode electrode 14 (y-axis direction in the drawing).

In the present exemplary embodiment, each of the cathode electrodes 14 may include a main electrode 141 extending along one direction of the first substrate 10 on the first substrate 10, and an auxiliary electrode formed on the main electrode 141. 142 and an adhesive layer 143 formed between the main electrode 141 and the auxiliary electrode 142 to secure the bonding force between the main electrode 141 and the auxiliary electrode 142.

The main electrode 141 is formed in a stripe shape having a constant width and is made of a transparent material, for example, indium tin oxide (ITO), for backside exposure of the electron emission unit, which will be described later.

The auxiliary electrode 142 is formed on the main electrode 141 to avoid electron emission region formation, and in order to compensate for the high resistance of the main electrode 141, the auxiliary electrode 142 may have a lower resistance value than the main electrode 141 or the adhesive layer 143. It may be formed of a metal material having, for example, silver (Ag) or aluminum (Al).

The adhesive layer 143 is formed between the main electrode 141 and the auxiliary electrode 142 to have a thickness of 500 to 800 占 in response to the auxiliary electrode, and is formed to have the same width or more as the auxiliary electrode 142 to be auxiliary. The electrode 142 and the main electrode 141 are separated.

The adhesive layer 143 may include a metal having excellent bonding strength with the main electrode 141 and the auxiliary electrode 142, for example, chromium (Cr) or titanium (Ti). Accordingly, since the etching material does not penetrate between the main electrode 141 and the auxiliary electrode 142 when etching to pattern the auxiliary electrode 142 (not shown), the auxiliary electrode 142 is the main electrode 141. It is possible to form an inclined side wall which becomes narrower as it is farther away from the? As a result, the step coverage of the auxiliary electrode 142 is good, and the occurrence of cracking in the first insulating layer 16 formed on the cathode electrode 14 is suppressed.

Meanwhile, although the adhesive layer and the auxiliary electrode are positioned in pairs for each of the main electrodes in the drawing, one adhesive layer and one auxiliary electrode may be provided for each of the main electrodes.

In the present exemplary embodiment, when the intersection area between the cathode electrode 14 and the gate electrode 18 is defined as a pixel area, one or more electron emission parts 20 are formed in each pixel area over the cathode electrodes 14.

In this case, the electron emission unit 20 may be formed through a known screen printing method, and may be formed by a backside exposure process that is exposed by irradiating ultraviolet rays from the backside of the first substrate 10. The first substrate 10 is prepared as a transparent substrate for backside exposure of the electron emitter 20, and the electron emitter 20 is formed on the transparent main electrode 141.

The electron emission unit 20 may be formed of materials emitting electrons, for example, carbon-based materials or nanometer-sized materials when an electric field is applied in a vacuum. The electron emission unit 20 may include, for example, a material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ), silicon nanowires, and combinations thereof. have.

Openings 181 and 201 corresponding to the electron emission parts 20 are formed in the first insulating layer 16 and the gate electrode 18 to expose the electron emission parts 20 on the first substrate 10.

The focusing electrode 22, which is a third electrode, is formed on the gate electrodes 18 and the first insulating layer 16. A second insulating layer 24 is positioned below the focusing electrode 22 to insulate the gate electrode 18 and the focusing electrode 22, and also to pass the electron beam through the focusing electrode 22 and the second insulating layer 24. Openings 221 and 241 are provided.

The focusing electrode forms an opening corresponding to each of the electron emission parts 20 to individually collect electrons emitted from each electron emission part 20, or forms one opening for each pixel area to emit light from one pixel area. The electrons can be comprehensively focused. 1 shows the second case.

Next, the light emitting unit 110 will be described. On one surface of the second substrate 12, the fluorescent layer 26, for example, the red, green, and blue fluorescent layers 26R, 26G, and 26B may be disposed on each other. It is formed at arbitrary intervals, and a black layer 28 for improving contrast of the screen is formed between each fluorescent layer 26. In the present exemplary embodiment, the fluorescent layer 26 is disposed so that the fluorescent layers 26R, 26G, and 26B of one color correspond to one pixel area.

An anode electrode 30 made of a metal film such as aluminum (Al) is formed on the fluorescent layer 26 and the black layer 28. The anode electrode 30 receives the high voltage required for electron beam acceleration from the outside of the vacuum container to maintain the fluorescent layer 26 in a high potential state, and toward the first substrate 10 of the visible light emitted from the fluorescent layer 26. The luminance of the screen is increased by reflecting the emitted visible light toward the second substrate 12.

The anode electrode may be made of a transparent conductive film such as indium tin oxide. In this case, the anode is positioned on one surface of the fluorescent layer 26 and the black layer 28 facing the second substrate 12. Moreover, the structure which forms simultaneously the above-mentioned metal film and a transparent conductive film as an anode electrode is also possible.

Spacers 32 (see FIG. 2) are disposed between the first substrate 10 and the second substrate 12 to counteract the compressive force applied to the vacuum vessel and to keep the distance between the two substrates 10 and 12 constant. do. The spacers 32 are positioned corresponding to the black layer 28 so as not to invade the fluorescent layer 26.

The electron emission display device having the above-described configuration may be driven by supplying a predetermined voltage to the cathode electrodes 14, the gate electrodes 18, the focusing electrode 22, and the anode electrode 30 from the outside.

For example, any one of the cathode electrodes 14 and the gate electrodes 18 receives a scan driving voltage to serve as scan electrodes, and the other electrodes receive a data driving voltage to serve as data electrodes.

The focusing electrode 22 receives a voltage required for focusing the electron beam, for example, a negative DC voltage of 0 volts (V) or several to several tens of volts (V), and the anode electrode 30 requires a voltage for accelerating the electron beam. For example, a positive DC voltage of hundreds to thousands of volts (V) is applied.

Then, an electric field is formed around the electron emission part 20 in the pixel areas in which the voltage difference between the cathode electrode 14 and the gate electrode 18 is greater than or equal to the threshold, and electrons are emitted therefrom. The emitted electrons are focused to the center of the electron beam bundle while passing through the opening 221 of the focusing electrode 22, and attracted by the high voltage applied to the anode electrode 30 to impinge on the fluorescent layer 26 of the corresponding pixel region. It emits light.

In the above driving process, the electron emission device according to the present invention forms an adhesive layer 143 between the main electrode 141 and the auxiliary electrode 142, thereby bonding the auxiliary electrode 142 to the main electrode 141. It is possible to secure the step coverage of the cathode electrode 14 by increasing the resistance, preventing the corrosion of the auxiliary electrode 142, and improving the etching characteristics of the auxiliary electrode 142.

In addition, the electron emission device of the present invention may form the auxiliary electrode 142 with a metal material having excellent conductivity, thereby lowering the resistance value of the cathode electrode 14, thereby enabling an operation at a low driving voltage.

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 electron emission device of the present invention can increase the bonding force between the main electrode and the auxiliary electrode by sequentially forming the adhesive layer and the auxiliary electrode on the main electrode as the cathode electrode. In addition, since the electron emission device according to the present invention lowers the resistance value of the cathode electrode by compensating the high resistance value of the main electrode as an auxiliary electrode, there is an effect capable of driving even at a low voltage.

Claims (10)

Board; A cathode electrode formed on the substrate; And An electron emission unit electrically connected to the cathode electrode, The cathode electrode, A main electrode extending in one direction of the substrate; An auxiliary electrode formed on the main electrode; And And an adhesive layer formed between the main electrode and the auxiliary electrode. The method of claim 1, And the adhesive layer is formed to a thickness of 500 to 800 GPa. The method of claim 1, And the adhesive layer comprises chromium (Cr) or titanium (Ti). The method of claim 1, And the auxiliary electrode is made of a material having a lower resistance value than the main electrode and the adhesive layer. The method of claim 4, wherein And the auxiliary electrode is formed of silver (Ag) or aluminum (Al). The method of claim 1, And one auxiliary electrode and one adhesive layer formed on each of left and right sides of the electron emission unit. The method of claim 1, And said main electrode is made of Indium Tin Oxide (ITO). The method of claim 7, wherein And an electron emitting device formed on the main electrode by an exposure process by ultraviolet rays irradiated from the rear surface of the substrate. The method of claim 1, And a gate electrode positioned insulated from said cathode electrode. The method of claim 1, And said electron emitting portion comprises at least one material selected from the group consisting of carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, fullerenes (C ₆₀ ) and silicon nanowires.

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