KR20050043206A - Surface conduction electron emitting device - Google Patents

Abstract

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a surface conduction field emission device, and in particular, to a surface conduction field emission device for stably forming a contact on an electrode and an emitter material to prevent defects that may occur in forming and to increase stability and reproducibility. It is about. In the conventional surface conduction field emission device, a very thin emitter thin film is formed on a relatively thick electrode, so that the contact portion is uneven due to the step difference between the two thin films, thereby increasing the corresponding partial resistance. In the forming process, since the contact with a large resistance is formed first, there is a fatal problem that deteriorates the characteristics of the uniform device, thereby degrading quality and reliability. In view of the above problems, the present invention forms an emitter thin film under the electrode, thereby placing an electrode on the emitter thin film to prevent an increase in contact resistance due to a step difference between two thin films having a large thickness difference. By providing a surface conduction field emission device that maintains a uniform distribution of resistance, uniform foaming can be performed at the center portion where heat is emitted most lately in the forming process, and the uniformity and reproducibility of the entire device can be extremely increased. As a result, the quality and reliability as well as the yield can be improved.

Description

Surface conduction field emission device {SURFACE CONDUCTION ELECTRON EMITTING DEVICE}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a surface conduction field emission device, and in particular, to a surface conduction field emission device for stably forming a contact on an electrode and an emitter material to prevent defects that may occur in forming and to increase stability and reproducibility. 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 flat panel display for overcoming all the disadvantages of flat panel displays (LCD, PDP, VFD, etc.) currently being developed or produced. The field emission device display has a simple electrode structure, high-speed operation based on the same principle as the CRT, and has the advantages that the display has such as infinite color, infinite gray scale, high luminance, and high video rate. have.

1 is a simple cross-sectional view for explaining the structure of a general field emission device, a cathode lower plate having an element layer 2 formed on a glass substrate 1, electrons provided by an electrode formed on the element layer 2, and An emitter 3 which emits electrons to the outside by an electric field, a focusing electrode 4 which focuses an electron beam emitted from the emitter 3, and a high voltage is applied to give direction to the emitted electrons. An anode top plate 7 to be applied, a fluorescent plate 8 to collide with the emitted electron beam to emit light, and a spacer for supporting between the cathode bottom plate and the anode top plate 7 and vacuuming the inside thereof (5) and a frit 6 for physically supporting the cathode lower plate and the anode upper plate 7.

The field emission display device having the above configuration 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 3) in the vacuum. At this time, the device exhibits the current-voltage characteristic according to the Fowler-Nordheim law.

The cathode bottom plate may be formed of various structures capable of emitting electrons and adjusting the position at which electrons are emitted. The illustrated structure shows a case where the cathode bottom plates 1, 2, and 3 are planar. In addition, there is a micro-tip field emission device in which the anode is conical. The tip from which electrons are emitted is sharpened to allow electric field concentration, and when the electron emission is induced, a voltage is applied to the gate electrode. To emit electrons. The emitter manufactured in the form of the micro tip has excellent electron emission characteristics, but it requires a large-scale equipment investment and a complicated manufacturing process to make a large area display device of 20 inches or more, and thus, it is much less competitive than other display devices.

  In contrast, most surface-emission display devices have a simple manufacturing process and structure, and there is no large barrier even when they are enlarged. Here, the operation of the surface conduction field emission device among the surface electron emission field emission devices will be described.

2 is a structure for showing the operation concept of the surface conduction field emission device, in which the electron emission part (emitter) 20 formed of PdO is narrowly formed in a part through a forming process in which a high voltage is applied. To form. When a voltage is applied to both ends of the emitter gap 25 (the gate electrode 11 and the cathode electrode 12), a high electric field is applied between the gaps, thereby causing electron emission. The emitted electrons are accelerated by the high voltage of the anode top plate 30 to collide with the phosphor (not shown).

As shown in the drawing, the surface conduction field emission device has a very simple structure, and is easy to be enlarged, and the structure forming process is simple. However, the process of forming the emitter 20 formed of PdO uses a process that is more difficult and time consuming than the process of forming an electrode structure. PdO is deposited. This will be explained in more detail.

FIG. 3 is a cross-sectional view showing a process of manufacturing an emitter of a conventional surface conduction field emission device. As shown in FIG. 3, electrodes 11 and 12 are formed on a glass substrate 10, and a Pd solution is formed therebetween. The PdO emitter 20 is formed by spraying by inkjet spraying.

First, as shown in FIG. 3A, the cathode electrode 12 and the gate electrode 11 are thickly formed on the glass substrate 10. The electrodes 11 and 12 are generally formed using a noble metal such as platinum so that a surface oxide film is not formed. The electrodes 11 and 12 should be formed thick in order to supply sufficient current to the surface conduction field emission unit having a relatively low efficiency.

Next, as shown in FIG. 3B, a Pd solution droplet 45 containing Pd is injected between the electrodes through the inkjet injection hole 40.

Next, as illustrated in FIG. 3C, the sprayed Pd solution droplet 45 is oxidized while being heat treated to form a PdO emitter 20 thin film. In this oxidation process, the surfaces of the electrodes 11 and 12 formed of the noble metal are not oxidized.

Next, as shown in FIG. 3D, a forming process of applying a high voltage to the PdO emitter 20 thin film is performed to form a gap in the PdO emitter 20 thin film. However, due to the unstable contact between the PdO emitter 20 and the electrodes 11 and 12, it may have a large contact resistance, and in this case, foaming may occur at a portion where the contact resistance is large, thereby inhibiting uniform device characteristics.

In more detail, the PdO emitter 20 has a very thin thickness of several nm, while the electrodes 11 and 12 are able to flow hundreds of electric currents to compensate for the low electron emission efficiency of the surface field emitter. It has a thick thickness of about nm. As described above, when the thickness difference between the two thin films is large, a very thin PdO thin film does not overcome the step of the electrode wiring, so that a part of the thin film partially broken is formed. That is, in the concept of the surface type field emission device, a thickness difference between the electrodes 11 and 12 and the emitter 20 is inevitably generated, and the emitter material 20 is formed while stably surrounding the electrode materials 11 and 12. It is very difficult to be. When there is a large thickness difference between the two materials, the electrical contact between the emitter material 20 and the electrodes 11 and 12 is not stable, and the resistance in the vicinity thereof increases significantly compared to the other parts of the emitter material 20. . Increasing the contact resistance causes a fatal problem in that a large amount of heat is generated in the contact region between the two materials having a high resistance during the forming process, thereby forming in the contact region.

4A illustrates a conventional structure in which tapered etching is applied such that the steps of the electrodes 11 and 12 are gradually changed to overcome the above steps. As shown, even if the electrode portion on which the emitter 20 is to be formed is inclined to prevent a sharp step, an increase in contact resistance occurs due to the step of the contact portion.

4B is an electron micrograph when the forming of the structure formed as shown in FIG. 4A is performed. As shown, it can be seen that foaming occurs in two portions where the inclination occurs. If the gap is not evenly formed between the two electrodes, the screen by the display element becomes uneven as a whole and the quality is greatly deteriorated. In addition, in severe cases, light emission may not be possible, and thus may be a bad pixel.

As described above, the conventional surface conduction field emission device forms a very thin emitter thin film on a relatively thick electrode, resulting in uneven contact due to the step difference between the two thin films, thereby increasing the corresponding partial resistance. In the forming process for forming the gap, since a large contact portion is formed first, there is a fatal problem that deteriorates the characteristics of the uniform device and thus deteriorates quality and reliability.

In view of the above problems, the present invention first forms an emitter thin film before forming an electrode, and forms an electrode on the upper part thereof, thereby placing an electrode on the upper part of the emitter thin film so that contact resistance due to a step difference between two thin films having a large thickness difference is achieved. The purpose of this invention is to provide a surface conduction field emission device which prevents an increase in source and maintains uniform distribution of resistance of the emitter thin film so that uniform foaming can be performed at the center portion where heat release occurs at the latest in the forming process. have.

The surface conduction field emission device of the present invention for achieving the above object includes a cathode electrode and a gate electrode formed on the same plane on the substrate; And an emitter material formed at the bottom of the electrodes while in contact with the cathode and gate electrodes.

If described in detail with reference to the accompanying drawings, the present invention as follows.

5A to 5C are cross-sectional views illustrating a manufacturing process of an exemplary embodiment of the present invention, in which the emitter material 55 is first formed, and then the electrodes 56 and 57 are formed thereon, as shown. The resistance distribution of the material 55 is kept even.

First, as shown in FIG. 5A, the emitter material is coated on the glass substrate 50 by an inkjet injection method using the inkjet injection hole 60.

Next, as shown in FIG. 5B, the emitter material 55 coated on the glass substrate 50 is heat-treated to form an emitter thin film. At this time, the internal resistance distribution of the emitter 55 formed of the emitter thin film is kept uniform.

Next, as shown in FIG. 5C, the gate electrode 56 and the cathode electrode 57 are applied with the electrode material so as to be spaced apart from each other while in contact with the emitter 55 at a portion on the formed emitter 55. Form through.

After the forming process, the central portion of the emitter 55 having a uniform resistance distribution is formed.

6A to 6D are cross-sectional views illustrating a manufacturing process of another embodiment of the present invention, in which the emitter material 55 is first formed, and then the electrodes 56 and 57 are formed thereon.

First, a glass substrate 10 as shown in FIG. 6A is prepared, and a photoresist 51 or another sacrificial layer is formed on the glass substrate 10 as shown in FIG. 6B, and then the emitter material is formed. Patterned according to the part to be formed. Then, the emitter material 55 is formed on the upper entire surface by a vacuum deposition method.

Next, as shown in FIG. 6C, the photoresist 51 and the emitter material thereon are removed to form an emitter thin film on the glass substrate 50. This is called a lift-off method. In this case, the emitter 55 formed also has an even distribution of resistance internally.

Next, the gate electrode 56 and the cathode electrode 57 are deposited on the formed emitter 55 so as to be spaced apart from each other while being connected to the emitter 55 in part.

After forming the electrodes 56 and 57 and the emitter 55 in the same manner as described above, a high voltage is applied to the electrodes 56 and 57 to form a gap in which the electrons are emitted to the emitter 55. When the forming process is performed, forming occurs in the central portion of the emitter 55 due to the uniform resistance distribution of the emitter 55. Therefore, the uniformity and reproducibility of the entire device can be extremely increased even by a simple change in the process sequence, thereby improving the quality and reliability as well as the yield.

Note that in addition to the methods described above, various processing techniques may be applied to form the emitter material at the bottom of the electrode material, and these various processing techniques may all be encompassed in the present invention. That is, by forming the emitter material at the lower end of the electrode, an increase in resistance due to unstable contact occurring at the contact portion of the two materials is prevented at the source.

As described above, the surface conduction field emission device of the present invention forms an emitter thin film under the electrode to prevent an increase in contact resistance due to a step difference between two thin films having a large thickness difference by placing an electrode on the emitter thin film. In addition, the uniform distribution of the emitter thin film enables uniform foaming at the central portion where heat dissipation occurs most lately in the forming process, thereby dramatically increasing the uniformity and reproducibility of the entire device. The reliability as well as the yield can be improved.

1 is a cross-sectional view showing a general structure of a conventional field emission device.

Figure 2 is a cross-sectional view showing the principle of operation of the conventional surface conduction field emission device.

Figure 3a to 3d is a cross-sectional view showing a conventional process for producing a surface conduction field emission portion of the inkjet injection method.

4A and 4B are electron micrographs of an emitter structure and an abnormal forming applied to a conventional tapered structure electrode.

Figures 5a to 5c is a cross-sectional view showing a manufacturing process of an embodiment of the present invention.

Figure 6a to 6d is a cross-sectional view showing a manufacturing process of another embodiment of the present invention.

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

50: glass substrate 51: photoresist

55 emitter 56 gate electrode

57: cathode electrode 60: inkjet jet

Claims (3)

 A cathode electrode and a gate electrode formed on the same plane on the substrate; And an emitter material formed at the bottom of the electrodes while in contact with the cathode electrode and the gate electrode at a portion thereof. 2. The surface conduction field emission device according to claim 1, wherein the emitter material is directly deposited on the substrate and then heat-treated, and the electrodes are formed by coating on the emitter material. The surface conduction field emission device according to claim 1, wherein the emitter material is formed by an inkjet coating method or a lift off method.