KR20020083007A - Field emission display device and manufacturing method of the device - Google Patents

Abstract

PURPOSE: An electro-luminescence display device and a method for fabricating the same are provided to form a strong electric field around a surface electron source by bending edges of a cathode electrode and a gate electrode. CONSTITUTION: A cathode electrode(6) and a gate electrode(8) are formed on a first substrate(2). An insulating layer(10) is used for insulating the cathode electrode(6) and the gate electrode(8). A plurality of surface electron sources(12) is formed on an edge portion of the cathode electrode(6) facing the gate electrode(8). An anode electrode(14) and a plurality of fluorescent layers(16R,16G,16B) are formed on a second substrate(4). A gate electrode line(18) of a stripe pattern is formed on a surface of the first substrate(2). The gate electrode line(18) is used as an address line for supplying voltage to the gate electrode(8). The insulating layer(10) is formed on an upper portion of the gate electrode line(18). A plurality of holes(10a) is formed on the insulating layer(10).

Description

Field emission display device and manufacturing method thereof {FIELD EMISSION DISPLAY DEVICE AND MANUFACTURING METHOD OF THE DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission display device. More particularly, the edges of the cathode electrode and the gate electrode are formed at an angle, and the gap between the two electrodes can be minimized to improve the focus characteristic of the electron while enabling low voltage driving. A field emission display device and a method of manufacturing the same are provided.

Recently, carbon materials having low work function and easy fabrication of surface type as an electron emission source of field emission display devices have been actively studied. Among them, carbon nanotubes (CNT; The radius of curvature of is extremely fine at about 100 GPa, and electrons are smoothly emitted even at an external voltage of about 10 to 50 V, which is expected to be an ideal electron emission source.

In addition to the above-mentioned CNTs, surface electron sources such as graphite and diamond-like carbon (DLC) are currently applied as emitters in a bipolar structure composed of a cathode electrode and an anode electrode. However, since the bipolar structure cannot accurately control the emitter current by using the voltage difference between the cathode electrode and the anode electrode, it is difficult to realize multi-color color image or video.

Therefore, a triode structure that further includes a gate electrode to control the emission current of the emitter has been proposed, and a structure in which the gate electrode is disposed on the side of the cathode in consideration of the focus characteristic of the electron has been proposed. In this structure, the electrons are generated in the horizontal direction from the emitter toward the gate electrode, and then move in the vertical direction by the anode electrode formed on the other substrate to reach the fluorescent film.

In connection with the above structure, U.S. Patent No. 6,060,113 forms a cathode electrode and a gate electrode side by side on a substrate, and forms a conductive thin film between the two electrodes. The structure which becomes is disclosed. As a result, the structure can easily control the electrons emitted from the crack according to the electric field applied to the conductive thin film, so that gray scale display has a good advantage.

However, if the crack does not completely occur in the conductive thin film, the cathode and the gate electrode may be shorted to cause pixel defects, and since there is no structural sharp edge near the electron emission region other than the crack, the structure may be strong in the sharp portion. The electric field is not available. In addition, since a large amount of current flows through the gate electrode in the driving process, high power consumption is required.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to form a lower angle between the cathode electrode and the gate electrode to induce a stronger electric field near the surface electron source to enable low voltage driving. To provide a field emission display device.

Another object of the present invention is to provide a field emission display device which can maintain a distance between the cathode electrode and the gate electrode substantially 10 μm or less to enable low voltage driving while suppressing beam spread of electrons to improve focus characteristics. have.

Another object of the present invention is to easily fabricate these electrodes such that the cathode and gate electrodes have more angled edges, effectively suppress the occurrence of short between the cathode and gate electrodes by the electron source, and between the two electrodes The present invention provides a method of manufacturing a field emission display device capable of accurately maintaining fine spacing.

1 is a cross-sectional view of a field emission display device according to a first embodiment of the present invention.

FIG. 2 is a plan view of the second substrate shown in FIG. 1. FIG.

3 is a partially enlarged view of FIG. 1;

4 is a partial perspective view of a field emission display device according to a second embodiment of the present invention.

5 is a cross-sectional view taken along the line A-A of FIG.

6 is a partial cross-sectional view of a field emission display device according to a third embodiment of the present invention.

7 to 13 are schematic views showing the manufacturing process of the field emission display device according to the present invention.

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

The first and second substrates,

A gate electrode line formed in a stripe pattern on the first substrate;

An insulating layer disposed on the front surface of the first substrate on the gate electrode line and forming a plurality of holes corresponding to the pixel region to expose a portion of the gate electrode line;

A plurality of gate electrodes formed to have a predetermined height over the insulating layer together with the inside of the hole of the insulating layer, and connected to the corresponding gate electrode lines;

A cathode formed in a stripe pattern perpendicular to the gate electrode line on the insulating layer;

A plurality of planar electron sources positioned at one edge of the cathode electrode facing the gate electrode, and maintained at a constant distance from the gate electrode;

Provided is a field emission display device comprising an anode electrode formed on the second substrate and a plurality of fluorescent films.

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

Forming a gate electrode line of a stripe pattern on the first substrate;

Forming an insulating layer on the front surface of the first substrate;

Patterning the insulating layer to form a plurality of holes corresponding to the pixel areas, exposing a portion of the gate electrode line through the holes;

Forming a lower end of the gate electrode by filling a conductive material in the hole of the insulating layer;

Forming a cathode of a stripe pattern perpendicular to the gate electrode line, together with an upper end connected to a lower end of the gate electrode on the insulating layer;

Forming a plurality of surface electron sources by applying an electron-emitting material to an edge of the cathode electrode facing the gate electrode;

Cutting off the edge of the surface electron source using a laser beam such that the surface electron source and the gate electrode are kept at a constant distance;

Forming an anode and a fluorescent film on the second substrate;

A method of manufacturing a field emission display device comprising the steps of integrally sealing the first and second substrates and evacuating the interior thereof.

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

1 is a cross-sectional view of a field emission display device according to a first embodiment of the present invention, and FIG. 2 is a plan view of the first substrate shown in FIG.

As shown, the field emission display device includes first and second substrates 2 and 4, a cathode electrode 6 and a gate electrode 8 formed on the first substrate 2, and insulates the two electrodes. A plurality of surface electron sources 12 formed at one edge of the insulating layer 10, the cathode electrode 6 facing the gate electrode 8, and the anode electrode 14 formed on the second substrate 4. And a plurality of fluorescent films 16R, 16G, 16B.

A gate electrode line 18 is formed in a stripe pattern on the surface of the first substrate 2 to function as an address line for supplying a voltage to the gate electrode 8, and the first substrate 2 over the gate electrode line 18. The insulating layer 10 is located over the entire surface.

The insulating layer 10 forms a plurality of holes 10a corresponding to the pixel area along the gate electrode line 18 to expose a portion of the gate electrode line 18 through the hole 10a. As a result, the gate electrode 8 is positioned inside the hole 10a of the insulating layer, and is electrically connected to the corresponding gate electrode line 18 to form an individual island type corresponding to each pixel region.

In addition, the cathode electrode 6 is formed on the insulating layer 10 in a stripe pattern perpendicular to the gate electrode line 18. Thus, the cathode electrode 6 and the gate electrode 8 are electrically insulated by the insulating layer 10, and are arranged side by side on each other so that the edges thereof face each other. In addition, a plurality of surface electron sources 12 are positioned at one edge (right edge of the drawing) of the cathode electrode 6 facing the gate electrode 8.

The surface electron source 12 is composed of a material having a low work function, typically carbon nanotubes (CNT), graphite, diamond-like carbon (DLC) or a mixture thereof, and the cathode is printed or deposited by a method such as It is formed in the surface type at the edge of the electrode (6).

Here, the cathode electrode 6 and the gate electrode 8 has a rectangular cross-sectional shape and forms a vertical edge. In particular, as shown in FIG. 3, the gate electrode 8 includes a lower end 8a positioned inside the hole of the insulating layer 10 and an upper end 8b having a predetermined height above the insulating layer 10. It is preferable that the edge of 8b is formed at the same height as the cathode electrode 6 so as to face the edge of the cathode electrode 6 and the surface electron source 12.

Since the surface electron source 12 is made of a conductive material, the surface electron source 12 may come into contact with the gate electrode 8 when applied to the edge of the cathode electrode 6 by printing or the like. As such, all of the surface electron sources 12 have edges 12a cut out with a laser beam facing the gate electrode 8. Therefore, the surface electron source 12 accurately maintains a minute gap with the gate electrode 8, and effectively blocks short generation between the cathode electrode 6 and the gate electrode 8.

In particular, the distance between the surface electron source 12 and the gate electrode 8 due to laser ablation is within about 10 μm, which is about 15 V / μm in the case of CNTs. This means that electron emission occurs at a voltage. As the gap between the cathode electrode 6 and the gate electrode 8 becomes smaller, the spreading of the electrons can be suppressed, which is advantageous in terms of the focus characteristic of the electrons.

Therefore, when a driving signal is supplied to the cathode electrode 6 and the gate electrode 8, an electric field is formed in the vicinity of the surface electron source 12 due to the voltage difference between these two electrodes. Since the edges of the cathode electrode 6 and the gate electrode 8 are both disposed, a stronger electric field is induced around the surface electron source 12 under the same voltage condition, so that electron emission is smoothly at the edge thereof.

As a result, the present embodiment enables effective low voltage driving, and the surface electron source 12 maintains an interval within 10 μm of the gate electrode 8, thereby suppressing the beam spreading of electrons in the driving process, thereby providing a separate focusing means. Even if not provided, the electrons emitted from the surface electron source 12 can be guided to the fluorescent film.

Here, since the electrons are generated toward the gate electrode 8 at the edge of the surface electron source 12 and then attracted by the high voltage of the anode electrode 14, the electrons show a tendency to proceed at an inclined angle with respect to the substrate. Instead of centering the center of the film 16 with the center of the surface electron source 12, it is preferable to dispose slightly to the right side of the drawing in consideration of the movement path of the electrons.

4 is a partially enlarged perspective view of a field emission display device according to a second exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view taken along line AA of FIG. 4, in which the cathode electrode 20 and the gate electrode 22 are mushrooms. As described above, the width of the insulating layer 10 is gradually increased toward the second substrate 4, so that the two electrodes form an angled edge near the surface electron source 12.

That is, in this embodiment, the cross section of the upper end portion 22b of the cathode electrode 20 and the gate electrode 22 has an inverted trapezoidal shape, and the angle between the upper surface facing the second substrate 4 and the side surface thereof is 90 ° or less. To form a more angled edge as compared to the previous embodiment. The structure of the cathode electrode 20 and the gate electrode 22 can be easily manufactured using a negative photosensitive material, the manufacturing process thereof will be described in detail below.

At the same time, in the present embodiment, the surface electron source 12 has the laser cut edge 12a facing the gate electrode 22 in the same manner as in the previous embodiment so that the gap between the gate electrode 22 and the gate electrode 22 is accurately maintained within 10 μm. .

Thus, according to the present embodiment, as the angled edges of the cathode electrode 20 and the gate electrode 22 are disposed near the surface electron source 12, the surface electron source is used under the same voltage condition by using a characteristic that an electric field is strongly applied to a pointed portion. Since a stronger electric field can be induced at (12), it has a more advantageous advantage for low voltage driving.

6 is a partially enlarged cross-sectional view of a field emission display device according to a third exemplary embodiment of the present invention. In this exemplary embodiment, the entire cathode electrode 24 and the gate electrode 26 are not formed on the cathode electrode. The upper end portion 26b of the structure is composed of CNTs, graphite, diamond-like carbon, or a mixture thereof, and emits electrons at the edges of the cathode electrode 24 and the gate electrode 26 by itself.

In addition, the upper end portion 26b of the cathode electrode 24 and the gate electrode 26 has a trapezoidal cross section in the same manner as in the second embodiment. As a result, the upper end 26b of the cathode electrode 24 and the gate electrode 26 has an angle of 90 ° or less between the upper surface facing the second substrate 4 and the side surface thereof so that the edge at which electrons are emitted becomes more angled. Form.

Therefore, in the present embodiment, when driving signals are supplied to the cathode electrode 24 and the gate electrode 26, a strong electric field is formed at the edges of these electrodes due to the voltage difference between the two electrodes, and electrons are simultaneously emitted from the edges of the two electrodes. In addition, the low voltage driving is possible due to the material characteristics and the shape characteristics of the cathode electrode 24 and the gate electrode 26.

Next, a method of manufacturing the field emission display device according to the present invention will be described. First, a process of manufacturing the structure of the first embodiment will be described.

To this end, first, silver paste is screen-printed on the surface of the first substrate 2 in a stripe pattern and baked to form a gate electrode line 18. In another embodiment, the gate electrode line 18 may be completed by screen printing a silver paste containing a photosensitive material on the entire surface of the first substrate 2 and patterning it by a photolithography process. (See Figure 7)

Subsequently, the glass paste containing silicon oxide is screen-printed several times on the entire surface of the first substrate 2 and then fired to form an insulating layer 10 having a thickness of approximately 20 μm. The insulating layer 10 is patterned to form a plurality of holes 10a corresponding to the pixel region, thereby exposing a portion of the gate electrode line 18 through the holes 10a. (See Figure 8)

In the patterning process of the insulating layer 10, a photoresist film (not shown) is formed on the insulating layer 10, and the film is partially exposed and developed to selectively remove only the portion where the gate electrode is to be located, and then the insulating layer 10 ) To form the holes 10a and remove the remaining photoresist film.

Next, the silver paste is completely printed on the insulating layer 10 to fill the silver paste in the hole 10a of the insulating layer 10, and the silver paste remaining on the surface of the insulating layer 10 is removed, followed by firing. (18) A lower end portion 8a of the gate electrode is formed in the hole 10a above. (See Figure 9A)

Subsequently, the photosensitive conductor paste in which the conductive material and the negative type photosensitive material are mixed is screen printed on the entire surface of the insulating layer 10, and leveled to form a flat photosensitive conductive layer 28 having a predetermined thickness. (See Figure 9B)

Since the negative type photosensitive material has a property of being cured by light, only an exposed portion corresponding to the gate electrode and the cathode electrode is selectively exposed and cured by using an exposure mask (not shown), and the remaining portion is removed by developing to form a cathode. The upper end 8b configuration of the electrode 6 and the gate electrode 8 is completed. (See Figure 9C)

Here, as the photosensitive conductor, for example, Fodel (trade name) of DuPont may be used. In this case, the cathode electrode 6 and the gate electrode 8 may be patterned at an interval of about 40 μm. Can be. As a result, the cathode electrode 6 and the gate electrode 8 are formed vertically on the surface of the insulating layer 10 at intervals of approximately 40 μm.

Subsequently, an electron emission material, typically CNT, graphite, diamond-like carbon or a mixture thereof, is printed or deposited at the edge of the cathode electrode 6 facing the gate electrode 8 to form the surface electron source 12. (See FIG. 10) The surface electron source 12 formed at this time is formed over the gate electrode 8 or the distance from the gate electrode 8 is not constant.

As a result, the edge of the surface electron source 12 facing the gate electrode 8 is cut out using a laser beam at an interval B of approximately 10 µm or less, preferably approximately 5 µm. (See FIG. 11) Accordingly, the surface electron source 12 is kept at a constant distance from the gate electrode 8 while blocking the short generation of the cathode electrode 6 and the gate electrode 8.

The second substrate 4 is prepared by using a transparent glass substrate, and a transparent indium tin oxide (ITO) conductive film is deposited on the entire surface of the second substrate 4 to form an anode electrode 14. The surface of the anode electrode 14 A plurality of fluorescent films 16R, 16G, and 16B corresponding to the cathode electrode 6 are formed in each of the fluorescent films 16, the respective centers of the electron paths of the electrons during assembly of the first substrate and the second substrate. The forming position is adjusted to face. (See Figure 12)

Finally, the periphery of these 1st and 2nd board | substrates 2 and 4 is sealed with a sealing material, and the inside is exhausted and the structure shown in FIG. 1 is completed.

On the other hand, the structure of the second embodiment described above is a structure in which the upper end portion 22b of the cathode electrode 20 and the gate electrode 22 gradually enlarges its area from the surface of the insulating layer 10 toward the second substrate 4. In the manufacturing method described above, when the photosensitive conductive layer 28 is formed on the entire surface of the insulating layer 10 as shown in FIG. 9B, and the photosensitive conductive layer 28 is selectively exposed, the light is substantially photosensitive conductive. Since the amount of light gradually decreases toward the bottom of the layer 28, the upper end portion 22b of the gate electrode 22 can be manufactured in the configuration shown in Figs.

Finally, the structure of the above-described third embodiment is formed by the electron emission material of the upper end 26b of the cathode electrode 24 and the gate electrode 26 itself instead of forming a separate surface electron source on the cathode electrode.

In the manufacturing method of the second embodiment, instead of the conductive material, a paste constituting the surface electron source, that is, CNT, graphite, diamond-like carbon or a mixture thereof and a negative photosensitive material, is placed on the entire surface of the insulating layer 10. By printing, the photosensitive electron emission layer 30 is formed (see FIG. 13), and the same process as described above is completed to complete the structure shown in FIG.

In this case, since the structure of the third embodiment does not include a separate surface electron source, the upper end portion 26b of the cathode electrode 24 and the gate electrode 26 is formed, and the surface electron source forming step and the laser ablation step are omitted. do.

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 enables the low voltage driving by forming the edges of the cathode electrode and the gate electrode to be more angled to induce a stronger electric field near the surface electron source. In addition, the present invention maintains the distance between the cathode electrode and the gate electrode to substantially 10㎛ or less to suppress the beam spreading of the electron to improve the focus characteristics of the electron, and has the advantage of suppressing the short generation of the cathode electrode and the gate electrode. .

Claims (16)

First and second substrates; A gate electrode line formed on the first substrate in a stripe pattern; An insulating layer disposed on an entire surface of the first substrate on the gate electrode line and forming a plurality of holes corresponding to the pixel area to expose a portion of the gate electrode line; A plurality of gate electrodes formed to have a predetermined height on the insulating layer together with the inside of the hole of the insulating layer and connected to the corresponding gate electrode lines; A cathode electrode formed on the insulating layer in a stripe pattern perpendicular to the gate electrode line; A plurality of surface electron sources positioned at one edge of the cathode electrode facing the gate electrode, the plurality of surface electron sources being spaced apart from the gate electrode; A field emission display device comprising an anode electrode and a plurality of fluorescent films formed on the second substrate. The method of claim 1, And the gate electrode includes a lower end disposed in the hole of the insulating layer, and an upper end having a predetermined height above the lower end. The method of claim 2, And an upper end portion of the gate electrode having the same height as the cathode electrode, wherein the edges of the cathode electrode and the gate electrode face each other. The method of claim 2, And a top portion of the cathode electrode and the gate electrode formed at right angles to the top surface and the side surface thereof. The method of claim 1, The surface electron source is a field emission display device consisting of carbon nanotubes, graphite, diamond-like carbon or a mixture thereof. The method of claim 1, The surface electron source has a laser cut edge facing the gate electrode to maintain a constant distance from the gate electrode. The method of claim 6, The surface electron source may face the gate electrode at intervals of 10 μm or less. The method of claim 2, And an upper end portion of the cathode electrode and the gate electrode having an angle between the upper surface and the side surface of 90 degrees or less. The method of claim 2, And an upper end portion of the cathode electrode and the gate electrode gradually widening from the surface of the insulating layer toward the second substrate to have an inverted trapezoidal cross-sectional shape. The method according to claim 8 or 9, And an upper end portion of the cathode electrode and the gate electrode to replace the surface electron source. The method of claim 10, And an upper end portion of the cathode electrode and the gate electrode made of carbon nanotubes, graphite, diamond-like carbon, or a mixture thereof. The method of claim 1, And the fluorescent film is disposed to be offset from the center of the surface electron source at regular intervals so as to face the center of the electron path. Forming a gate electrode line of a stripe pattern on the first substrate; Forming an insulating layer on the front surface of the first substrate; Patterning the insulating layer to form a plurality of holes corresponding to the pixel regions, and exposing a portion of the gate electrode line through the holes; Filling a conductive material in the hole of the insulating layer to form a lower end of the gate electrode; Forming a cathode of a stripe pattern perpendicular to the gate electrode line, together with an upper end connected to a lower end of the gate electrode on the insulating layer; Forming a plurality of planar electron sources by applying an electron-emitting material to an edge of the cathode electrode facing the gate electrode; Cutting off edges of the surface electron source using a laser beam such that the surface electron source and the gate electrode maintain a constant distance; Forming an anode electrode and a fluorescent film on a second substrate; And integrally sealing the first and second substrates and evacuating the interior of the first and second substrates. The method of claim 13, Forming an upper end of the gate electrode and a cathode electrode, A paste in which the conductive material and the negative photosensitive material are mixed is printed on the entire surface of the insulating layer to form a photosensitive conductive layer; Selectively exposing only a portion of the photosensitive conductive layer corresponding to the upper end portion of the gate electrode and the cathode electrode to cure it; Developing the photosensitive conductive layer to remove the uncured portion. The method of claim 13, Forming upper ends of the cathode electrode and the gate electrode; A paste in which the electron emission material and the negative photosensitive material are mixed is printed on the entire surface of the insulating layer to form a photosensitive electron emission layer; Selectively exposing only a portion of the photosensitive electron emission layer corresponding to the upper end of the gate electrode and the cathode electrode to cure it; Developing the photosensitive electron emission layer to remove the uncured portion, And forming a surface electron source and cutting off an edge of the surface electron source. The method of claim 13, And cutting the edge of the surface electron source to cut at intervals of 10 μm or less from the gate electrode.