KR19990043864A - Manufacturing method of field emission display device - Google Patents

Abstract

The present invention relates to a method for manufacturing a triode type field emission display device. After depositing a DLC thin film or a carbon thin film as an emitter forming material on a cathode metal layer, the deposited DLC thin film or carbon thin film is subjected to a high power laser. By forming into a polycrystalline diamond by liquid crystallization, the uniformity of the emission characteristics of the polycrystalline diamond can be obtained, and at the same time, a large area can be achieved by a low temperature process, and amorphous silicon is deposited as a gate electrode forming material. After that, the amorphous silicon is formed of polycrystalline silicon at the same time by the same process of forming the liquid crystallization, thereby simplifying the process.

Description

Manufacturing method of field emission display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a field emission display (hereinafter referred to as a FED), in which polycrystalline diamond is manufactured at low temperature and applied to a field emission device, thereby improving emission characteristics, manufacturing a large area, and lifetime. The present invention relates to a method for manufacturing a triode type field emission display device capable of improving process yield and device reliability due to extension and simplification of the manufacturing process.

The thin film type field emission device is a device that emits cold electrons by tunnel effect by applying a relatively low voltage, for example, a voltage of about 5 to 10V, by using a phenomenon in which an electric field is concentrated on a sharp part of a tip. FED has attracted attention as a next-generation display device because it has both the high definition of CRT and the light and thin advantages of liquid crystal display (LCD).

In particular, the FED can not only manufacture the thin and thin, but also solve the problems of process yield, manufacturing cost, and enlargement, which are crucial disadvantages of the LCD.

That is, in case of LCD, even if one unit pixel is defective, the whole product is treated badly. However, FED has a smaller number of unit pixels in one pixel group, so even if one or two unit pixels are defective, There is no problem in operation, and the yield of the whole product is improved.

In addition, FED has advantages such as simple structure, low power consumption, low unit cost, and suitable for portable display device.

Initially, the FED is exposed to the outside by a cavity, and has a conical emitter having sharp parts, a gate arranged on both sides of the emitter, and an electrode to which a fluorescent plate is attached at a predetermined distance from the gate. Each of which corresponds to a cathode, a grid and an anode of the CRT.

In the FED, a predetermined voltage, for example, a voltage of about 500 to 10 mA is applied and electrons are emitted by an electric field concentrated at the top of the emitter, and the emitted electrons are delivered by an anode to which a positive voltage is applied. To emit the fluorescent material applied to the anode, and the gate controls the direction and amount of electrons.

However, in the early FED having the conical cathode as described above, some of the emitted electrons are induced to the gate, so that the gate current flows to control the electrons, and cations formed by colliding with the electrons between the cathode and the anode, Since the device is destroyed by collision, in order to prevent this, the inside of the device must be maintained in a high vacuum state, and there is a problem that it is difficult to uniformly manufacture a sharp conical cathode.

In addition, since a high voltage is required at the anode and the gate electrode, application to a portable display device is difficult.

In order to solve these problems, a thin film type field emission device has been proposed, in which three conductive thin films insulated from each other are sequentially installed on a substrate conductor, and a part of the three conductive thin films is formed to protrude through the cavity. Proposed structure of the anode by installing an external electrode on the upper side.

The thin film type field emission device having such a structure applies a negative voltage to a cathode, which is a conductive thin film located at the center, and emits electrons by applying an alternating voltage to gate conductive thin films located on both sides of the cathode, and is strong to the substrate conductor. A negative voltage is applied to cause electrons emitted from the cathode to strike the anode, which is an external electrode.

As the thin film type field emission display device according to the related art, a device using silicon as a substrate and an electrode is attracting attention due to its easy manufacturing method and material selection. Such a silicon device has a cathode tip made of polycrystalline silicon on a silicon substrate. Forming a gate insulated from the cathode by forming a wet etching method using a nitride film pattern as an etching mask, applying an oxide film and a metal film to the entire surface, and removing the nitride film pattern by a lift off method. Used.

In the method of manufacturing the field emission display device by the lift-off process using the silicon material according to the prior art as described above, the short circuit between the tip and the gate is likely to occur, the tip is damaged, and the process yield and the uniformity are poor. There is a problem such as lowering the reliability of device operation.

In order to solve the above problem, conventionally, diamond or pseudo-diamond (DLC) materials are used to emit electric fields using chemical stability, low electron affinity, and high resistance to ions. It has been used to apply to the device and to coat the top of the tip.

1 is a cross-sectional view showing the structure of a triode type field emission display device using a conventional DLC.

As shown in the drawing, in the triode type field emission display device using the conventional DLC, the metal layer 2 of the cathode is formed on the lower substrate 1, and the DLC thin film 5 and the gate are formed thereon. The insulating layer 7 and the gate metal electrode 9 are formed, and the upper substrate 17 having the phosphor 13 is provided at a position spaced apart from the lower substrate 1 by a predetermined distance.

Problems in the structure of the conventional triode type field emission display device formed as described above are largely as follows.

That is, the first is the case of the polycrystalline diamond formed in the high temperature process, in this case, because the high temperature process, the process cost is high, the process progress is difficult, and also when forming a large area to increase the area.

Secondly, as DLC, in this case, the process can be carried out at a low temperature, but in the subsequent process, when the temperature rises to a certain temperature, for example, 300 ° C. or more, the characteristics of the thin film are changed to deteriorate the characteristics of the field emission display device.

In other words, diamond has a high manufacturing temperature, DLC is a material having a low temperature, but a lack of resistance to temperature, and polycrystalline diamond having a higher emission characteristics than the DLC is a different material due to the high manufacturing temperature, for example, Since a material of a material such as a silicon substrate or a ceramic must be used as a substrate, there is a problem in that it is difficult to manufacture a large area FED.

The present invention is to solve the above problems, an object of the present invention is to coat the DLC or amorphous carbon, the liquid phase crystallization (liquid phase crystallization) of the upper layer of the material using a laser can also be used for the glass substrate It is possible to manufacture a polycrystalline diamond field emission device having excellent emission characteristics as well as a field emission which can simplify the manufacturing process by manufacturing polycrystalline silicon by liquid crystallizing the gate electrode material in the same process at the same time. The present invention provides a method for manufacturing a display device.

1 is a cross-sectional view showing the structure of a triode type field emission display device using a conventional DLC.

2A to 2C are sectional views showing a manufacturing process sequence of a triode type polycrystalline diamond field emission display device by laser annealing according to the present invention;

<Explanation of symbols for main parts of drawing>

1,21: lower substrate 3,23: cathode metal layer

5,25 DLC thin film 7,27 Gate insulating film

9,29 gate metal electrode 11 electron emission beam

13: phosphor 17: upper substrate

15: Indium Thin Oxide (ITO)

25 ': polycrystalline diamond 29': polycrystalline silicon

31: laser light

The present invention for achieving the above object,

Forming a metal layer as a cathode electrode material on the substrate, forming a DLC thin film as an emitter forming material, a gate electrode made of amorphous silicon, and a gate insulating film separating the gate electrode and the cathode, respectively, on the cathode metal layer In the method for manufacturing a field emission display device,

After depositing the DLC thin film, the upper layer portion of the DLC thin film is subjected to liquid crystallization by heat treatment using a high power laser to form polycrystalline diamond.

Hereinafter, a method of manufacturing a triode type field emission display device according to the present invention will be described in detail with reference to the accompanying drawings.

2A and 2B are manufacturing process diagrams of a triode type field emission display device according to the present invention.

Referring to FIG. 2A, the cathode metal layer 23 is formed by depositing and patterning a metal, which is a cathode electrode material, on a lower substrate 21 made of a glass substrate or a silicon substrate.

Thereafter, a DLC thin film 25, an emitter forming material, a gate electrode 29 made of amorphous silicon, and a gate insulating layer 29 separating the gate electrode 29 and the cathode are formed on the cathode metal layer 13. .

In this case, a carbon thin film may be deposited instead of the DLC thin film 15.

Referring to FIG. 2B, the upper layer of the DLC thin film 25 is liquid crystallized using a high power laser to form the DLC thin film 25 as polycrystalline diamond.

The above process results in a local temperature rise only in the upper layer of the thin film and the lower thin film has no effect.

The polycrystalline diamond of the present invention formed as described above can adjust the size of the diamond crystals, that is, the grain size, according to variables such as power or time of the laser, resulting in improved uniformity of emission characteristics.

2C is a cross-sectional view of a triode type polycrystalline diamond field emission display device manufactured according to the method of the present invention.

In the drawing, the DLC thin film 25 and the amorphous silicon 29, which is a gate electrode forming material, are formed of amorphous diamond 25 'and polycrystalline silicon 29', respectively, in an upper layer thereof due to liquid crystallization by a laser.

As described above, in the present invention, in forming a triode type field emission display device, a DLC thin film or a carbon thin film, which is an emitter forming material, is deposited on a cathode metal layer, and then the deposited DLC thin film or carbon thin film is deposited. Formation of polycrystalline diamond by liquid crystallization using a laser of power enables to obtain uniformity of emission characteristics of the polycrystalline diamond, and at the same time, a large area can be achieved by a low temperature process. In addition, since amorphous silicon is deposited as a gate electrode forming material and the amorphous silicon is simultaneously formed of polycrystalline silicon by the same process of forming liquid crystallization, the process can be simplified, thereby improving reliability by improving device characteristics. You can.

Claims (5)

Forming a metal layer as a cathode electrode material on the substrate, forming a DLC thin film as an emitter forming material, a gate electrode made of amorphous silicon, and a gate insulating film separating the gate electrode and the cathode, respectively, on the cathode metal layer In the method for manufacturing a field emission display device, After depositing the DLC thin film, a method of manufacturing a triode type field emission display device characterized in that the liquid crystallization of the upper layer portion of the DLC thin film by a heat treatment process using a high power laser to produce a polycrystalline diamond. The method of claim 1, wherein the lower substrate is formed of any one of glass, silicon, and ceramic. The method of manufacturing a triode type field emission display device according to claim 1, wherein an amorphous carbon thin film is used instead of the DLC material. The method of manufacturing a triode type field emission display device according to claim 1, wherein the metal layer is formed of one material arbitrarily selected from the group consisting of Mo, Nb, W, Cr, Ta, or Ti. The method of manufacturing a triode type field emission display device according to claim 1, wherein the amorphous silicon which is a gate electrode forming material is formed of polycrystalline silicon during the heat treatment process using the laser.