KR20020031819A - Manufacturing method for field emission display - Google Patents

Abstract

PURPOSE: A method for fabricating an FED(Field Emission Display) device is provided to form a fine CNT(Carbon Nano Tube) emitter by using a CMP(Chemical Mechanical Polishing) method. CONSTITUTION: A cathode electrode(32) is formed on a rear substrate(30). A screen layer is formed on an overall surface of the above structure. An emitter hole is formed by removing partially the screen layer. A CNT(44) is applied on the overall surface of the above structure by using a screen print method. The emitter hole is buried by the CNT(44). The CNT(44) is etched by using the screen layer pattern as an etch stop layer. The screen layer pattern is removed. An emitter is formed by using the CNT(44). An anode electrode(52) and a fluorescent material(54) are formed on a front substrate(50). An FED is completed by bonding the front substrate(50) and the rear substrate(30).

Description

Manufacturing method for 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 FED), in particular forming a fine CNT emitter by chemical mechanical polishing (hereinafter referred to as CMP), and controlling current The present invention also relates to a method of manufacturing a FED which can also form a cathode electrode for the purpose of miniaturization of a pixel and an easy current control to improve process yield and reliability of device operation.

The thin film type field emission device is a device that emits cold electrons by tunnel effect by applying a relatively low voltage by using a phenomenon in which the electric field is concentrated on the sharp part of the tip. The liquid crystal display (hereinafter referred to as LCD) has all the advantages of the light and thin type, attracting attention as a next generation display device. 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.

In other words, if a single unit pixel is defective, the entire product will be treated as defective. However, FED has a smaller number of emitter tips formed in one pixel group. There is no abnormality in the operation of the group, which improves the overall product yield.

In addition, the FED has a simple structure compared to the LCD, low power consumption, low cost, there are some advantages suitable for the portable display device.

Initially, the FED is exposed to the outside by a cavity, and has a conical emitter tip having a sharp portion, a gate arranged on both sides of the emitter to control the amount of current, and a fluorescent plate spaced apart from the gate at a predetermined interval. It consists of an attached anode electrode, each of which corresponds to a cathode, a grid and an anode of the CRT.

In the FED, when a predetermined voltage, for example, a voltage of about 500 to 10 mA is applied, electrons are emitted by an electric field concentrated at the tip of the emitter tip, and the emitted electrons are applied to an anode to which a positive voltage is applied. Guides the light emitting 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, it is necessary to maintain the inside of the device in a high vacuum state in order to prevent such a high vacuum maintenance is difficult, there is a problem such as difficult to uniform production of sharp cone-shaped 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 FED 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 a strong negative to the substrate conductor. A voltage is applied to cause electrons emitted from the cathode to strike the anode, which is an external electrode.

As a thin film type FED according to the prior art, a device using silicon as a substrate and an electrode has been attracting attention because of its easy manufacturing method and material selection. Such a silicon device uses a cathode tip made of polycrystalline silicon on a silicon substrate to form a nitride film pattern. A method of forming a gate insulated from the cathode by forming a wet etching method used 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.

In the manufacturing method of the FED 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 reproducibility and uniformity of the process are reduced. There is a problem such as lowering the reliability.

In order to solve the above problem, diamond or similar diamond (Diamond-Like Carbon; DLC) material having a chemical stability, low electron affinity, high resistance to ions, and the like applied to the field emission device tip The method of coating on the top of or using CNT as an emitter which is excellent in field emission property is especially studied.

1 is a cross-sectional view of a FED according to the prior art, which is an example of an FED using CNT as an emitter.

First, a cathode electrode 12 is formed on a back substrate 10 made of silicon, glass, or the like, and an adhesive layer 14 and a CNT 16, which are emitters, are formed on the cathode electrode 12. The anode electrode 22 and the phosphor 24 are formed on the front substrate 20 thereon.

CNT used in the FED according to the prior art as described above has excellent field emission characteristics, but since CNT is formed by the screen printing method, the unit pixel is formed to be about 100 μm, so that it is difficult to miniaturize, thereby limiting the reliability of the device. Since there is no gate structure, there is a problem that the current cannot be adjusted.

The present invention is to solve the above problems, an object of the present invention is to provide a fine CNT emitter having a gate electrode by the CMP method to reduce the size of the unit pixel and facilitate the control of the current process yield and It is to provide a method of manufacturing a FED that can improve the reliability of device operation.

1 is a cross-sectional view of an FED using CNTs according to the prior art.

Figures 2a to 2g is a manufacturing process of the FED according to an embodiment of the present invention.

Figure 3a to 3g is a manufacturing process of the FED according to another embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10,30: back substrate 12,32: cathode electrode

14: adhesive layer 16, 44: CNT

20,50: front substrate 22,52: anode electrode

24, 54 phosphor 34 gate insulating film

36 gate electrode 40 insulating film

42 emitter hole 60 screen film

The characteristics of the field emission display device according to the present invention to achieve the above object,

Forming a cathode on the back substrate;

Forming a screen film pattern having an emitter hole on the structure;

Applying a CNT to the entire surface of the structure to fill the emitter holes;

Removing the upper portion of the CNT to leave only the CNT filling the emitter hole;

The surface of the remaining CNTs is CNT surface treatment to form an emitter tip.

In addition, the back substrate is formed of a silicon wafer or glass material, and the screen film is formed of a photoresist film or an insulating film, and if the screen film is a photosensitive film, a screen film pattern is formed by an exposure and development process, and if the screen film is an insulating film Or a nitride film, and a screen film pattern is formed by front coating and photolithography.

In addition, the CNT coating process is carried out by a screen printing method, the upper etching process of the CNT is carried out by the CMP method, the front substrate is formed of glass, quartz or plastic, the screen film pattern is removed before the CNT surface treatment CNT surface treatment is performed.

In addition, another feature of the present invention,

Forming a cathode on the back substrate;

Forming a gate insulating film and a gate metal layer on the entire surface of the structure;

Patterning the gate metal layer and the gate insulating layer to form a gate electrode exposing a cathode electrode;

Forming an insulating film on the entire surface of the structure;

Forming an emitter hole in the insulating film;

Applying a CNT to the entire surface of the structure to fill the emitter holes;

Removing the upper portion of the CNT to leave only the CNT filling the emitter hole;

And a process of forming an emitter tip by CNT surface treatment of the upper surface of the remaining CNTs.

The gate insulating film is formed of an oxide film or a nitride film.

Hereinafter, a manufacturing method of the FED according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 2a to 2g is a manufacturing process of the FED according to an embodiment of the present invention.

First, the cathode electrode 32 is formed on the rear substrate 30 (see FIG. 2A), and the screen film 60 is formed on the entire surface of the structure, and patterned to form the screen film of the portion intended as the emitter region. 60 is removed to form an emitter hole 42 exposing the cathode electrode 32. The screen layer 60 may be formed of an insulating film such as a photosensitive film, an oxide film, or a nitride film. In the case of the photosensitive film, a pattern may be formed by exposure and development. In the case of the insulating film, the pattern may be formed by a photolithography process. (See FIG. 2B).

Then, CNTs 44 were applied to the entire surface of the structure by screen printing to fill and planarize the emitter holes 42 (see FIG. 2C), and then, by using the screen layer 60 as an etch stop layer, by CMP method. The CNTs 44 are etched so that only the CNTs 44 filling the emitter holes 42 remain. (See FIG. 2D)

Thereafter, the screen film 60 pattern was removed, and CNT surface treatment was performed (see FIG. 2E) to form an emitter made of CNT 44 to complete the back substrate 30 (see FIG. 2F). An anode electrode 52 and a phosphor 54 are formed on the front substrate 50, and the anode electrode 52 and the phosphor 54 are sealed, and the sealed interior is sealed under vacuum to complete the FED. (See FIG. 2G).

After the process of FIG. 2D, the emitter tip may be formed by performing CNT surface treatment without removing the screen layer 60 pattern, and may form the unit pixel finely to about 10 μm, and not the rear substrate. The miniaturization of the pixel is determined according to the miniaturization degree of the formed front substrate.

3A to 3G are diagrams illustrating a manufacturing process of the FED according to another embodiment of the present invention.

First, the cathode electrode 32 is formed on the rear substrate 30 (see FIG. 3A), the gate insulating film 34 and the gate metal layer are coated on the entire surface of the structure, and then patterned by a photolithography process. A gate electrode 36 exposing the cathode electrode 32 is formed. The gate insulating film 34 is formed of an oxide film or a nitride film. (See Figure 3b).

Then, an insulating film 40 for preventing a short circuit is applied to the entire surface of the structure by using an oxide film or a nitride film material, and then the insulating film 40 in the portion scheduled for the emitter region is removed by a photolithography process to remove the cathode electrode 32. After the emitter hole 42 is formed (see FIG. 3C), the CNT 44 is applied to the entire surface of the structure by a screen printing method to fill and planarize the emitter hole 42. (See FIG. 3D).

Thereafter, using the insulating film 40 as an etch stop layer, the CNT 44 was etched by the CMP method so that only the CNT 44 filling the emitter hole 42 was left (see FIG. 3E). Thereby protruding the upper surface of the remaining CNTs 44 to form an emitter tip. (See FIG. 3F).

Then, the insulating film 40 is removed to complete the back substrate 30 process, and an anode electrode 52 and a phosphor 54 are formed on the front substrate 50 made of a transparent material, and the back substrate 30 and Seal to complete the FED. (See FIG. 3G).

The back substrate 30 is formed of silicon or glass, the cathode electrode 32 is formed of a low resistance metal, for example Cr, and the front substrate 50 is made of glass, quartz or plastic. It is formed of a transparent material.

As described above, the manufacturing method of the FED according to the present invention is to form a screen film pattern having an emitter hole formed by a photolithography process, apply CNT to the front surface by screen printing, and then remove the upper CNT by the CMP method. Since the emitter tip was formed by CNT surface treatment after leaving only the portion of the emitter hole filled with CNTs, the gate electrode can be easily formed and the unit pixel can be minutely formed, so that the current control of the device is easy and the image quality is easy. This improvement has the advantage of improving process yield and reliability of device operation.

Claims (15)

Forming a cathode on the back substrate; Forming a screen film pattern having an emitter hole on the structure; Applying a CNT to the entire surface of the structure to fill the emitter holes; Removing the upper portion of the CNT to leave only the CNT filling the emitter hole; CNT surface treatment of the surface of the remaining CNTs to form an emitter tip. The method of claim 1, The back substrate is a manufacturing method of the FED, characterized in that formed of a silicon wafer or glass material. The method of claim 1, A method of manufacturing an FED, wherein the screen film is formed of a photosensitive film or an insulating film. The method of claim 3, wherein If the screen film is a photosensitive film, the manufacturing method of the FED characterized in that to form a screen film pattern by the exposure and development process. The method of claim 1, When the screen film is an insulating film formed of an oxide film or a nitride film, a method of manufacturing a FED, characterized in that to form a screen film pattern by the front coating and photolithography method. The method of claim 1, Method for producing a FED characterized in that the CNT coating step is performed by a screen printing method. The method of claim 1, Method for producing a FED, characterized in that to perform the upper etching process of the CNT by the CMP method. The method of claim 1, The front substrate is a field emission display device, characterized in that formed of one material arbitrarily selected from the group consisting of glass, quartz and plastic. The method of claim 1, And removing the screen film pattern before the CNT surface treatment to perform CNT surface treatment. Forming a cathode on the back substrate; Forming a gate insulating film and a gate metal layer on the entire surface of the structure; Patterning the gate metal layer and the gate insulating layer to form a gate electrode exposing a cathode electrode; Forming an insulating film on the entire surface of the structure; Forming an emitter hole in the insulating film; Applying a CNT to the entire surface of the structure to fill the emitter holes; Removing the upper portion of the CNT to leave only the CNT filling the emitter hole; CNT surface treatment of the remaining surface of the CNT to form an emitter tip. The method of claim 10, The back substrate is a manufacturing method of the FED, characterized in that formed of a silicon wafer or glass material. The method of claim 10, The gate insulating film is formed of an oxide film or a nitride film. The method of claim 10, Method for producing a FED characterized in that the CNT coating step is performed by a screen printing method. The method of claim 10, Method for producing a FED, characterized in that to perform the upper etching process of the CNT by the CMP method. The method of claim 10, The front substrate is a method of manufacturing a field emission display device, characterized in that formed of one material arbitrarily selected from the group consisting of glass, quartz and plastic.