KR20050096527A - Cathode plate of field emission display and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a cathode substrate of a field emission display device and a method of manufacturing the same. The cathode substrate of the field emission display device according to the present invention comprises a cathode electrode formed in a stripe shape on a light transmissive substrate in a first direction, and a non-metallic material having an ultraviolet transmittance of less than 5%, and having a portion of the cathode electrode exposed thereto. An insulating layer having a hole and covering the substrate and the cathode electrode, a gate electrode having an opening corresponding to the gate hole on the insulating layer and formed in a stripe shape in a second direction perpendicular to the first direction, and formed in the gate hole And an electron emission source electrically connected to the cathode electrode.

Description

Cathode substrate of field emission display device and method for manufacturing same {Cathode plate of field emission display and method for manufacturing the same}

The present invention relates to a cathode substrate of a field emission display device and a method of manufacturing the same.

Recently, various liquid crystal display (LCD), plasma display panel (PDP), electroluminescent display (ELD), field emission display (FED), etc. Displays are being researched and developed.

Field emission displays using carbon nanotubes combine the advantages of a cathode ray tube (CRT) with excellent image characteristics such as high definition, high resolution, and wide viewing angle, and a flat panel display featuring light weight, thinness, and low power consumption. It is an ideal display. Such field emission displays can be used in various fields such as monitors of various computers, camcorders, high-definition digital televisions, wall-mounted televisions, car navigation systems, view finders of electronic imaging devices, and the like.

The field emission display device basically includes a cathode substrate and an anode substrate. The cathode substrate refers to a lower structure portion of the field emission display device that emits electrons by applying an electric field to the electron emission source, and the anode substrate refers to a portion that emits light by accelerating collision of electrons emitted from the electron emission source with the phosphor.

An example of a cathode substrate of a field emission display device is disclosed in Korean Patent Laid-Open Publication No. 2003-63529. A conventional cathode substrate will be described below.

1 is a cross-sectional view of an example of a cathode substrate of a conventional field emission display device. The cathode substrate 100 shown in FIG. 1 has a triode structure and includes a carbon nanotube electron emission source 114 as an electron emission source. Hereinafter, the carbon nanotube electron emission source will be briefly referred to as carbon nanotube.

Referring to FIG. 1, the cathode substrate 100 includes a substrate 102, a cathode electrode 104, a mask cathode layer 106, an insulating layer 108, a gate electrode 110, a gate hole 112, and carbon. Nanotubes 114. The substrate 102 is formed of glass, and the mask cathode layer 106 is formed of a metal layer or an ultraviolet blocking material such as amorphous silicon. The insulating layer 108 transmits ultraviolet rays.

The mask cathode layer 106 is patterned prior to the formation of the insulating layer 108 so that the cathode electrode 104 in the region where the carbon nanotubes 114 are to be formed is exposed. The carbon nanotubes 114 are formed by a front surface coating through a patterned photoresist sacrificial layer (not shown), followed by a backside exposure, development, cleaning, and baking process.

2 is a cross-sectional view of another example of a cathode substrate of a conventional field emission display device.

Referring to FIG. 2, the cathode substrate 200 includes the substrate 202, the cathode electrode 204, the insulating layer 206, the gate electrode 208, the gate hole 210, the ultraviolet blocking resistive layer 212, and carbon. Nanotubes 214. The insulating layer 206 basically transmits ultraviolet rays. The UV blocking resistive layer 212 blocks incident light of the backside exposure so that only the carbon nanotube paste (not shown) in the region where the cathode electrode 204 is exposed on the bottom surface reacts with the exposure light.

The UV blocking resistive layer 212 covers the insulating layer 206, the gate hole 210 and the gate electrode 208 on which the cathode electrode 204 is exposed on the bottom surface before the carbon nanotube 214 is formed. It is formed to. Thereafter, the UV blocking resistive layer 212 is patterned so that the formation region of the carbon nanotubes 214 is removed.

As described above, the above-described conventional cathode substrate includes a step of forming a mask cathode layer or an ultraviolet blocking resist layer so that carbon nanotubes are formed only in a specific region and residues thereof do not remain in the manufacturing method thereof.

However, in the conventional cathode substrate, since the mask cathode layer or the UV blocking resist layer usually contains a metal component such as chromium (Cr), the breakdown voltage characteristic between the cathode substrate or the cathode electrode and the gate electrode is weakened depending on the content of the metal component. there is a problem. In addition, the manufacturing process of the cathode substrate is complicated because a process of depositing a mask cathode layer or a UV blocking resist layer and patterning a mask cathode layer or an UV blocking resist layer using a photosensitive layer and a mask is required. There is this.

In addition, the conventional method of manufacturing a cathode substrate uses a back exposure method of forming carbon nanotubes using a photoresist as a sacrificial layer to form a carbon nanotube electron emission source. Hereinafter, the back exposure method using the sacrificial layer will be briefly described.

3 is a view for explaining a method of manufacturing a cathode substrate using a conventional back exposure method.

Referring to FIG. 3, the cathode substrate 300 includes a substrate 302, a cathode electrode 304, an insulating layer 306, a gate electrode 308, a gate hole 310, a photoresist sacrificial layer 312, and carbon. Holes 314 defining nanotube forming regions, and carbon nanotubes 316. The photoresist sacrificial layer 312 is applied onto the entire surface of the substrate 302 prior to the process of forming the carbon nanotubes 316 and patterned to include the holes 314. Thereafter, a carbon nanotube paste (not shown) is applied to the entire surface of the photoresist sacrificial layer 312, and a carbon nanotube 316 is formed through a backside exposure, development, cleaning, and baking process.

In the conventional method of manufacturing a cathode substrate, the carbon nanotubes 314 are formed in a limited portion of the photoresist sacrificial layer 312 in a region smaller than the gate hole 314. Accordingly, there is a problem that the effective area of the carbon nanotubes 314 that contributes to the emission is reduced in the cathode substrate by the conventional manufacturing method. In addition, the conventional manufacturing method has a limitation in that the exposure dose cannot be maximized because the photoresist and carbon nanotubes of the sacrificial layer react with the exposure light during the backside exposure process.

On the other hand, if the conventional cathode electrode manufacturing process does not include additional processes such as a mask cathode layer forming process or a UV blocking resist layer forming process, ultraviolet rays transmitted through the insulating layer react with the photoresist sacrificial layer and the carbon nanotube paste. As a result, residues of carbon nanotubes remain on the cathode substrate upon removal of the carbon nanotubes unreacted with the photoresist sacrificial layer. For example, when a residue of carbon nanotubes is left between the gate electrode and the carbon nanotubes or the cathode electrode, a short circuit occurs between the gate electrode and the carbon nanotubes or the cathode electrode, which causes the electron emission source in the cathode substrate to be broken. . As a result, this causes a change in the number of electron emission sources included in one pixel of the field emission display device, making it difficult to display desired luminance on an arbitrary pixel, or reducing the luminance of the pixel to reduce the uniformity of the display device.

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to omit the photoresist sacrificial layer process during the formation of the carbon nanotubes of the cathode substrate, thereby manufacturing the cathode substrate and the field emission display device. The present invention provides a method for manufacturing a cathode substrate of a field emission display device that can be simplified.

Another object of the present invention is to provide a cathode substrate of a field emission display device capable of displaying relatively high brightness by increasing the effective area of carbon nanotubes, and a method of manufacturing the same.

In order to achieve the above object, according to an aspect of the present invention, a cathode electrode formed in a stripe shape on a light transmissive substrate in a first direction, and a portion of the cathode electrode made of a non-metallic material having an ultraviolet transmittance of less than 5% An insulating layer having a gate hole to which the substrate is exposed and covering the substrate and the cathode electrode, a gate electrode formed in a stripe shape in a second direction perpendicular to the first direction on the insulating layer, and formed in the gate hole and electrically connected to the cathode electrode. A cathode substrate of a field emission display device including an electron emission source connected thereto is provided.

According to another aspect of the invention, forming a cathode electrode extending in a stripe shape in a first direction on the transparent substrate, forming an insulating layer having a UV transmittance of less than 5% on the substrate and the cathode electrode, the insulating layer Forming a metal layer thereon; forming a gate hole in the metal layer and the insulating layer so that a portion of the cathode electrode is exposed; and having an opening corresponding to the gate hole, the opening being formed at a predetermined distance from the edge of the gate hole. Patterning the metal layer as a gate electrode, forming an electron emission source located in the gate hole and electrically connected to the cathode electrode, carbon nanowire on the insulating layer, the gate electrode, and the gate hole exposed to the cathode electrode on the bottom surface Applying a tube paste and irradiating light from the back side of the substrate to This step, and the method of manufacturing a carbon nanotube field emission display the cathode substrate of the device including the non-exposed portion of the paste to the step of development is provided to expose the nanotubes paste.

It is preferable that the above-mentioned insulating layer is a nonmetallic series. At this time, the insulating layer does not contain chromium (Cr).

The developing of the non-exposed portion of the carbon nanotube paste described above preferably includes an alkaline developing process capable of producing a large area product.

The method of manufacturing the cathode substrate of the field emission display device described above preferably further comprises firing carbon nanotubes as electron emission sources.

Next, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. no.

4 is a cross-sectional view of a cathode substrate of an EL display device according to a first embodiment of the present invention.

Referring to FIG. 4, the cathode substrate 400 includes a substrate 402, a cathode electrode 404, an insulating layer 406, a gate electrode 408, and a carbon nanotube 410. The insulating layer 406 includes a gate hole 412 in which carbon nanotubes 410 are formed.

The cathode electrode 404 is exposed to the bottom surface of the gate hole 412. The gate electrode 408 has a recess 414 at the edge of the opening of the gate hole 412. The step portion 414 is to maintain a predetermined interval so that the carbon nanotubes 410 and the gate electrode 408 formed inside the gate hole 412 are not short-circuited with each other.

Substrate 402 includes a glass substrate. Cathode electrode 404 includes a transparent electrode. The transparent electrode includes indium tin oxide (ITO). The cathode electrode 404 is preferably patterned in a stripe shape. In this case, the gate electrode 408 is patterned to extend in a direction substantially perpendicular to the cathode electrode 404.

The insulating layer 406 is formed of a nonmetallic material. The nonmetal-based material includes either a ceramic-based material containing SiOx or PbO as a main component and a material containing SiN as a main component.

The carbon nanotubes 410 may be made of a low work function carbon-based material composed of holene (C ₆₀ ), diamond, diamond-like taso (DLC), graphite, or a combination thereof. In particular, the carbon nanotubes 410 are formed of a material which is chemically and mechanically compatible with the cathode electrode material placed on the bottom and the device materials on the top.

As such, the cathode substrate according to the present invention may include the carbon nanotubes 410 increased to an arbitrary height within an appropriate limit using the maximum exposure amount because the insulating layer 406 transmits less than 5% of ultraviolet light of the exposure light. have. In addition, the cathode substrate of the present invention is coated with a carbon nanotube paste (not shown) directly into the gate hole 412 without forming a sacrificial layer using a photoresist using a material having a UV transmittance of less than 5% as the insulating layer 406. As a result, the effective area may include carbon nanotubes 410 increased.

Next, a method of manufacturing the cathode substrate of the field emission display device according to the present invention will be described in detail with reference to FIGS. 5A to 5G.

Referring to FIG. 5A, a cathode electrode 404, an insulating layer 406, and a metal layer 408a are sequentially formed on the substrate 402. The cathode electrode 404 may be patterned into a predetermined shape by a photolithography process according to the size and number of each device before forming the insulating layer 406. For example, the transparent electrode ITO is deposited on the glass substrate 402 using a sputtering method to form the patterned cathode electrode 404 through an etching process. Meanwhile, the cathode electrode 404 may be formed by screen printing by ITO paste having a viscosity and a solid component suitable for printing.

The insulating layer 406 is formed by forming a thick film insulating layer by screen printing an entire surface of the insulating material and then performing dry firing. The insulating material of the insulating layer 406 includes a non-metallic material having an ultraviolet transmittance of less than 5%. For example, an insulating material mainly composed of a ceramic material such as SiOx or PbO may be used.

The metal layer 408a is formed as a thin film layer on the entire surface of the insulating layer 406 by using thin film equipment such as a sputter. The metal layer 408a is formed of at least one metal selected from aluminum, chromium, tantalum, and molybdenum. On the other hand, the metal layer 408a may be formed by a method of screen printing and printing a metal paste, followed by heat treatment to dry the metal paste.

5B and 5C, a gate hole 412 is formed in the insulating layer 406 and the metal layer 408b through a photolithography process. In order to form the gate hole 412, a photoresist is first applied to the entire surface of the metal layer 408b, and then a photoresist layer 416 having a gate hole pattern is formed through an exposure and development process. In the photolithography process, a mask 418 for forming a gate hole pattern is used. The metal layer 408a is etched using the photoresist layer 416 as a mask, and the metal layer 408b having the gate hole etching pattern 414a is formed.

Thereafter, the insulating layer 406 is etched using the metal layer 408b on which the gate hole etching pattern 414a is formed as a mask. The photoresist layer 416 is peeled off. Through this process, the insulating layer 406 is formed with a gate hole 412 exposing the cathode electrode 404 on the bottom surface.

5D to 5F, the metal layer 408b is patterned so that the stepped portion 414 is formed at the edge of the opening of the gate hole 412 by a photolithography process. In addition, the metal layer 408b is patterned, for example, in a stripe shape extending in a direction orthogonal to the cathode electrode 404. The gate electrode 408 is formed by this process.

To form the gate electrode 408, first a photoresist is applied to the entire surface on the substrate of FIG. 5C. 5D and 5E, the photoresist layer 420 having the gate electrode pattern is formed through the photolithography process. In the photolithography process, a mask 422 for forming a gate electrode pattern is used. The metal layer 408b is etched using the photoresist layer 420 having the gate electrode pattern formed thereon. Thereafter, as shown in FIG. 5F, the photoresist layer 420 is peeled off to form the gate electrode 408. By the above-described process, the stripe gate electrode 408 having the stepped portion 414 is formed. 5F, the cathode electrode 404, the insulating layer 406 having the gate hole 412, and the gate electrode 408 having the stepped portion 414 are sequentially stacked on the substrate 402. The cathode electrode 404 is exposed through the bottom surface 412a of the gate hole.

Referring to FIGS. 5G and 5H, for example, screen printing may be performed on the inside of the gate hole 412 including the bottom surface 412a of the gate hole, the stepped portion 414, and the carbon nanotube paste 410a on the gate electrode 408. By coating and drying. Then, the exposure process is performed using the backside exposure method. When exposure light is transmitted from the rear surface of the substrate 402, the carbon nanotube paste 410a is cured in response to the exposure light. In other words, almost all ultraviolet rays of the exposure light are transmitted through the bottom surface side of the gate hole 412 in which the insulating layer 406 is not formed. Therefore, the carbon nanotube paste 410a is cured to a predetermined height according to the exposure amount. As described above, according to the present exemplary embodiment, the curing height of the carbon nanotubes can be adjusted by maximizing the exposure amount when forming the carbon nanotubes as the electron emission source. In addition, the insulating layer 406 of the present invention has an ultraviolet transmittance of less than 5%. Therefore, the carbon nanotube paste 410a reacts only in the region of the gate hole 412 where the insulating layer 406 is not formed.

When the carbon nanotubes 410 are formed in the gate hole 412, the unexposed portions of the carbon nanotube paste 410a are developed and removed by an alkaline developing method. Alkaline development indicates the use of alkaline materials as developer. Here, the carbon nanotube paste 410a contains a photosensitive material. Therefore, the unexposed carbon nanotube paste 410a can be easily removed by an alkaline developing process.

Referring to FIG. 5I, after the above-described process, in order to improve the characteristics as the electron emission source, the element including the carbon nanotubes 410 is fired at a predetermined temperature and the surface treatment process is performed on the carbon nanotubes 410. Perform.

Meanwhile, in the conventional carbon nanotube forming process, carbon nanotubes are developed using, for example, sodium carbonate (Na ₂ CO ₃ ) (0.4 wt%) to remove the photoresist sacrificial layer and carbon nanotube paste, and then sodium hydroxide. (NaOH) is used to lift off the sacrificial layer. As another method, in the conventional carbon nanotube forming process, the photoresist sacrificial layer and the carbon nanotube paste are lifted off together using acetone which easily dissolves the photoresist. However, the conventional method using sodium carbonate or sodium hydroxide is complicated by removing the carbon nanotube paste and the sacrificial layer, respectively. In addition, the method using acetone is advantageous in the process because it removes the sacrificial layer and the carbon nanotube paste at the same time, but the acetone development process is configured to use the ultrasonic equipment together, there is a disadvantage that the large area equipment is not easily available. In addition, in the conventional method using sodium carbonate or acetone, residues of unexposed carbon nanotube paste remain without being dissolved in the developer, or a part of the exposed carbon nanotube paste is exposed to the developer so that the residue is exposed to the gate electrode or It may be attached to an insulating layer or the like. This may cause defects such as short-circuits between the electrodes of the cathode substrate of the triode structure and diode emission due to the anode voltage.

However, the present invention can be applied to the alkaline development method that is easy to use the large-area equipment for the formation of carbon nanotubes. Accordingly, there is an advantage in that a large area of the cathode substrate is easy and a large area uniformity is improved when manufacturing a large area emission display device. Furthermore, in the present invention, since the carbon nanotube paste is easily removed by the alkaline developer, defects such as short-circuit between electrodes or diode emission due to anode voltage which may occur in the conventional carbon nanotube forming process can be prevented.

In the above-described embodiment, the formation of the electron emission source using the carbon nanotube paste has been described. However, the present invention is not limited to such a configuration, and various materials that can be applied with the photosensitive paste can be used for forming the electron emission source.

In the above-described embodiment, the cathode substrate of the field emission display device has been described. However, the field emission display device according to the present invention may include an anode substrate including a front substrate, an anode electrode, and a fluorescent surface in addition to the cathode substrate. In this case, the cathode substrate and the anode substrate can be bonded in a vacuum state by the sealing material while being kept at a predetermined interval by the space.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

According to the present invention, the photoresist sacrificial layer may be omitted when the carbon nanotubes are formed in the cathode substrate manufacturing process of the field emission display device, thereby simplifying the manufacturing process of the cathode substrate and the field emission display device.

In addition, according to the present invention, by omitting a photoresist sacrificial layer and coating a carbon nanotube paste directly in the gate hole, the field emission display device having a relatively high luminance can be displayed by increasing the effective area of the carbon nanotubes as the electron emission source. Can provide.

In addition, according to the present invention, there is an advantage that can increase the height of the carbon nanotubes further can increase the back exposure amount relative to the conventional.

In addition, according to the present invention, since the photoresist sacrificial layer is omitted and the photosensitive carbon nanotube paste can be directly formed by an alkaline developing method that can use a large area equipment, a field emission display device having improved large area uniformity can be provided. have.

1 is a cross-sectional view of an example of a cathode substrate of a conventional field emission display device.

2 is a cross-sectional view of another example of a cathode substrate of a conventional field emission display device.

3 is a view for explaining a method of manufacturing a cathode substrate of a conventional field emission display device.

4 is a cross-sectional view of a cathode substrate of a field emission display device according to an exemplary embodiment of the present invention.

5A to 5I are views illustrating a method of manufacturing a cathode substrate of a field emission display device according to an exemplary embodiment of the present invention.

<Description of the symbols in the main part of the drawing>

400: cathode substrate 402: substrate

404: cathode electrode 406: insulating layer

408: gate electrodes 408a and 408b: metal layer

410: carbon nanotube electron emission source 410a: carbon nanotube paste

412: gate hole 414: stepped portion

414a: concave

Claims (5)

Translucent substrate; A cathode electrode formed on the substrate; An insulating layer made of a non-metallic material having an ultraviolet transmittance of less than 5% and having a gate hole through which a portion of the cathode electrode is exposed and formed on the cathode electrode layer; A gate electrode formed on the insulating layer and having an opening corresponding to the gate hole; And And a cathode emission source formed in the gate hole and electrically connected to the cathode electrode. Forming a cathode electrode on the light transmissive substrate; Forming an insulating layer having an ultraviolet transmittance of less than 5% on the substrate and the cathode electrode; Forming a metal layer on the insulating layer; Forming a gate hole in the metal layer and the insulating layer to expose a portion of the cathode electrode; Patterning the metal layer into a gate electrode; Forming an electron emission source positioned in the gate hole and electrically connected to the cathode electrode; And And applying an electron emission source paste on the gate hole where the insulating layer, the gate electrode, and the cathode electrode are exposed, and exposing the backside, and then developing a non-exposed portion of the electron emission source paste. Method for producing a cathode substrate. The method of claim 2, And the insulating layer is formed of a non-metal based material. The method of claim 3, The non-metal-based material includes any one material selected from SiOx, PbO and SiN. The method of claim 2, And developing the non-exposed portion of the residue emission source paste comprises an alkaline development process.