KR100548257B1 - Field emission device - Google Patents

Abstract

The present invention relates to a field emission device suitable for reinforcing insulation of a gate electrode and an insulating layer in an undergate structure using carbon nanotubes as a field emission emitter, and preventing short circuits between the electrodes. A gate electrode, a diffusion barrier layer formed on the gate electrode, a diffusion barrier layer for preventing short circuit and insulation, an insulation layer sequentially formed on the diffusion barrier layer, and a cathode electrode having carbon nanotubes formed on a portion of the gate gate, There is an effect of preventing a short circuit between the electrodes and a short circuit between the cathode electrode and the gate electrode, and strengthening the insulation of the insulating layer and the gate electrode.

Description

Field emission device {FIELD EMISSION DEVICE}

1 is a cross-sectional view showing an example of the bottom plate structure of a three-electrode field emission device using a conventional carbon nanotube.

Figure 2 is a plan view and a cross-sectional view showing a bottom plate structure for the field emission device of the undergate structure using a conventional carbon nanotube.

3 is a cross-sectional view showing a bottom plate structure of the field emission device of the undergate structure of the present invention.

** Description of the symbols for the main parts of the drawings **

20: glass substrate 21: gate electrode

22: insulating layer 23: cathode electrode

24: Carbon nanotube 25: Diffusion prevention film

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a field emission device, and more particularly to a field emission device suitable for reinforcing the insulation of the gate electrode and the insulating layer in an undergate structure using carbon nanotubes as the field emission emitter, and for preventing short circuits between the electrodes. It is about.

 Due to the rapid development of information and communication technology and the demand for the visualization of diversified information, the demand for electronic displays is increasing and the required display appearance is also diversified. For example, in an environment where mobility is emphasized such as a portable information device, a display having a small weight, volume, and power consumption is required, and when used as an information transmission medium for the public, display characteristics of a large viewing angle are required.

In addition, in order to satisfy such demands, electronic displays require conditions such as large size, low price, high performance, high definition, thinness, and light weight, so that light and thin that can replace the existing CRT are required to satisfy these requirements. There is an urgent need for the development of flat panel display devices.

Recently, as the needs of various display devices have been applied to display fields, devices using field emission have been actively developed for thin film displays that can provide high resolution while reducing size and power consumption.

The field emission device is attracting attention as a next-generation information communication flat panel display that overcomes all the disadvantages of flat panel displays (LCD, PDP, VFD, etc.) currently being developed or produced. The field emission device has a simple electrode structure, high-speed operation using the same principle as the CRT, and has the advantages of display such as infinite color, infinite gray scale, high brightness, and high video rate. .

The field emission device utilizes a quantum mechanical tunneling phenomenon in which electrons exit the vacuum from the metal or conductor when a high field is applied to the metal or conductor surface (emitter) in the vacuum. At this time, the device exhibits the current-voltage characteristic according to the Fowler-Nordheim law. The field emission device is composed of an anode portion which emits an electron emission source and the emitted electrons collide with each other to emit light, a spacer supporting the upper and lower plates, and a sealing portion for maintaining a vacuum tightness.

Recently, the importance of the field emission device using the carbon nanotubes (CNT) because of the mechanically strong, chemically stable and excellent electron emission characteristics at a relatively low vacuum degree has been recognized. Since such carbon nanotubes have a small diameter (about 1.0 to several tens of nanometers), the field enhancement factor is considerably superior to the conventional microtip type spin emission field emission tips, and thus the emission threshold is low. Since it can be made in a turn-on field (about 1 to 5 [V / μm]), there is an advantage of reducing power loss and production cost.

1 is a cross-sectional view showing an example of the bottom plate structure of a three-electrode field emission device using a conventional carbon nanotube. As shown, the resistive layer 12, the insulating layer 14, and the gate electrode 15 are sequentially formed on the silicon substrate 11, and the gate electrode 15 and the insulating layer 14 are formed by photolithography. After etching a portion to form a hole, the catalyst transition metal layer 13 is formed on the resistive layer 12 at the bottom of the hole through evaporation, and the entire silicon substrate 11 is about 600-900 [deg.] C. The carbon nanotubes 16 are selectively formed only on the catalyst transition metal layer 13 through a thermal chemical vapor deposition method using a hydrocarbon gas or a plasma chemical vapor deposition method by heating to a temperature range. .

In this case, since the carbon nanotubes 16 are selectively formed only on the catalyst transition metal layer 13, the larger the area of the catalyst transition metal layer 13, the larger the area of the carbon nanotubes 16. As such, when the area of the carbon nanotubes 16 increases, the electric field applied through the gate electrode 15 is not concentrated, so that the beam of the emitted electrons is spread and the electron emission region is not even. Only the electron emission is likely to occur locally, and due to an asymmetric electric field distribution, the leakage current to the gate electrode 15 has many problems.

In order to solve the above problems, the structure of the carbon nanotube field emission device having the gate electrode positioned at a lower position than the cathode electrode has been proposed.

2 is a plan view and a cross-sectional view of an example of a bottom plate structure in a field emission device having an under gate structure using a conventional carbon nanotube. As shown, the gate electrode 21 and the cathode electrode 23 on the glass substrate 20 have a matrix structure that is orthogonal to each other with the insulating layer 22 interposed therebetween. The method is applied to the gate electrode 21 under the tube 24.

Referring to the manufacturing process of the bottom plate structure for the field emission device of the undergate structure as follows.

First, an Indium-Tin-Oxide (ITO) transparent electrode is deposited on the glass substrate 20 to a thickness of about 120 nm, and the gate electrode 21 is formed by using a photolithography method. (21) The dielectric powder in the form of a paste is coated on the top by screen printing, and fired at about 580 [deg.] C to form the insulating layer 22.

A conductive metal such as aluminum (Al) or chromium (Cr) is deposited on the insulating layer 22 to a predetermined thickness, and then vertically intersects with the gate electrode 21 using a photolithography method to form the cathode electrode 23. The carbon nanotubes 24 are formed at the edges of the cathode electrode 23.

However, a pinhole is generated in the insulating layer 22 formed through the firing of the dielectric powder, and when the cathode electrode 23 is formed, a short circuit may occur with the gate electrode 21 through the pinhole.

In addition, the tin (Sn) component included in the ITO electrode used as the gate electrode 21 exits the ITO electrode base material as the plastic is fired, and the resistance of the gate electrode rapidly increases, and Na + diffuses in the glass substrate 20 component. There is a problem that may cause a short circuit between the gate electrodes.

In the field emission device having an undergate structure using a conventional carbon nanotube as described above, a pinhole is generated in an insulating layer formed by firing dielectric powder, and a gate electrode previously formed under the insulating layer through the pinhole when a cathode is formed. There was a problem that can cause a short circuit.

Further, is a tin (Sn) components contained in the ITO electrode used as a gate electrode to escape from the ITO electrode base material in accordance with the firing of the insulating layer is a surge in the gate electrode resistance, Na ⁺ diffuse from the glass substrate constituents gate electrode There was a problem that a short circuit could occur.

Therefore, in view of the above problems, the present invention provides a short-circuit between gate electrodes in a field emission device having an undergate structure by forming a diffusion barrier using a ceramic material having high transmittance and excellent insulation between the gate electrode and the insulating layer. And a field emission device capable of preventing a short circuit between the cathode electrode and the gate electrode, and enhancing the insulation of the insulating layer and the gate electrode.

The present invention for achieving the above object is a gate electrode formed on the lower substrate; A diffusion barrier layer formed on the gate electrode, the diffusion barrier layer for short circuit prevention and insulation; And a cathode electrode having carbon nanotubes formed in an insulating layer and a partial region sequentially formed on the diffusion barrier.

The material of the diffusion barrier film is a ceramic material having high transmittance and excellent insulation.

The diffusion barrier is made of SiO ₂ or SiN _x .

With reference to the accompanying drawings, a preferred embodiment of the field emission device of the present invention having the above characteristics will be described.

Figure 3 shows a cross-sectional view of the bottom plate structure for the field emission device of the undergate structure using the carbon nanotube of the present invention. As shown, a diffusion prevention film is added between the gate electrode and the insulating layer in the lower plate structure of the field emission device having the conventional undergate structure, the gate electrode 21 formed on the glass substrate 20 and the gate A diffusion barrier layer 25 formed on the electrode 21 to prevent a short circuit between the gate electrode 21 and another electrode (cathode electrode), a short circuit prevention and an insulation between the gate electrodes, and an upper portion of the diffusion barrier layer 25. And the cathode electrode 23 formed on the insulating layer 22 formed on the insulating layer 22 and having the carbon nanotubes 24 formed on a portion of the insulating layer 22.

The diffusion barrier 25 has a high transmittance such as SiO ₂ or SiN _x , and is excellent in insulation and is made of a ceramic material.

Then, the manufacturing process for the present invention having such a configuration will be described.

First, an Indium-Tin-Oxide (ITO) transparent electrode is deposited on the glass substrate 20 to a thickness of about 120 nm, and the gate electrode 21 is formed using a photolithography method.

Next, a diffusion barrier 25 is formed on the gate electrode 21 by sputtering, chemical vapor deposition, or dipping a ceramic material such as SiO ₂ or SiN _x .

The paste-type dielectric powder is coated on the diffusion barrier layer 25 by screen printing, and then fired at about 580 [deg.] C to form an insulating layer 22 having a thickness of about 10 [[micro] m].

A conductive metal such as aluminum (Al) or chromium (Cr) is deposited on the insulating layer 22 to a thickness of about 300 [nm], and then vertically intersects with the gate electrode 21 using a photolithography method to form a cathode. An electrode 23 is formed, and a carbon nanotube 24 is formed at the edge of the cathode electrode 23.

In this case, the carbon nanotubes 24 formed at the edges of the cathode electrode 23 may form the carbon nanotubes in the form of a paste by a printing method, or may be accurately drawn using a lift-off method. It is also possible to form an island).

The diffusion barrier layer 25 of the field emission device thus formed prevents the tin (Sn) component from being contained in the base material of the gate electrode 21 when firing the dielectric powder formed thereon, thereby increasing the resistance of the gate electrode 21. And short circuit with the gate electrode 21 through the pinhole present in the insulating layer 22 when the cathode electrode 23 is formed, and also prevents a short circuit between the gate electrodes.

As described in detail above, the present invention provides a short-circuit between gate electrodes by forming a diffusion barrier layer using a ceramic material having high transmittance and excellent insulation between the gate electrode and the insulating layer in the field emission device having an undergate structure. There is an effect to prevent a short circuit between the cathode electrode and the gate electrode, and to strengthen the insulation of the insulating layer and the gate electrode.

Claims (3)

A gate electrode formed on the lower substrate; A diffusion barrier layer formed on the gate electrode, the diffusion barrier layer for short circuit prevention and insulation; And a cathode electrode having carbon nanotubes formed in an insulating layer and a partial region sequentially formed on the diffusion barrier layer. The field emission device according to claim 1, wherein the material of the diffusion barrier film is a ceramic material having high transmittance and excellent insulation. The field emission device according to claim 1 or 2, wherein the diffusion barrier is made of SiO ₂ or SiN _x .

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