KR20070078901A - Manufacturing method of electron emission device - Google Patents

Abstract

A manufacturing method of an electron emission device is provided to secure a vertical property of an electron emission unit by forming additionally a second mask layer having a low reaction property with an electron emission unit. A plurality of cathode electrodes(4), an insulating layer(6), and a plurality of gate electrodes(8) are formed on a substrate(2). A plurality of apertures are formed in the gate electrodes and the insulating layer. A mask layer is formed on an entire surface of the substrate. An aperture(201) is formed at a part for forming an electron emission unit by patterning the mask layer. The electron emission unit is formed by screen-printing a mixture containing an electron emission material on an aperture(161) of the mask layer. A method for forming the mask includes a process for forming a first mask layer; a process for forming an aperture on the part for forming the electron emission unit; and a process for forming an aperture having a vertical sidewall at the part for forming the electron emission unit by patterning the second mask layer.

Description

Manufacturing Method of Electron Emission Device {MANUFACTURING METHOD OF ELECTRON EMISSION DEVICE}

1A-1F are schematic diagrams at each manufacturing step shown to illustrate a method of manufacturing an electron emitting device according to an embodiment of the present invention.

2 is a partially exploded perspective view of an electron emission display device to which an electron emission device manufactured according to an exemplary embodiment of the present invention is applied.

TECHNICAL FIELD The present invention relates to an electron emitting device, and more particularly, to a method of manufacturing an electron emitting device capable of increasing the shape uniformity of an electron emitting portion.

In general, an electron emission element may be classified into a method using a hot cathode and a method using a cold cathode according to the type of electron source.

Here, the electron-emitting device using the cold cathode is a field emitter array (FEA) type, a surface conduction emission type (SCE) type, a metal-insulation layer-metal Metal (MIM) type and Metal-Insulator-Semiconductor (MIS) type are known.

The field emission array (FEA) type electron emission device includes an electron emission unit and a driving electrode for controlling electron emission of the electron emission unit, including one cathode electrode and one gate electrode, and a work function as a constituent material of the electron emission unit. Materials with low or high aspect ratios, such as carbon nanotubes and carbon-based materials such as graphite and diamond-like carbon, utilize the principle that electrons are easily released by an electric field in vacuum.

The electron emission elements are arranged in an array on one substrate to form an electron emission device, and the electron emission device is combined with another substrate provided with a light emitting unit composed of a fluorescent layer and an anode electrode, and the electron emission display device. (electron emission display device) is configured.

The electron emission device may be formed by stacking driving electrodes, an insulating layer, and an electron emission portion. For example, a known field emission array (FEA) type electron emission device has cathode and insulating layers and gate electrodes sequentially formed on a substrate, and openings are formed in the gate and insulating layers to expose a portion of the surface of the cathode electrode. The electron emission portion is disposed on the cathode electrodes inside the opening.

As a process of forming an electron emitting portion in the above-described structure, a method of growing an electron emitting material directly on a cathode electrode, a method of screen printing a paste-like mixture containing an electron emitting material on a cathode electrode, and the like are known.

Among them, the screen printing method forms a mask layer over the entire surface of the structure provided on the substrate and pattern it to form an opening at the electron emission region formation position, screen-print the mixture over the substrate, and selectively select the mixture filled in the opening. And then the uncured mixture is removed and the mask layer is peeled off. In this case, the mask layer is usually made of a photoresist layer, and is patterned by exposure and development to form an opening.

However, since the mask layer is formed over the opening sidewall of the insulating layer, and unintentional portions are exposed together by light scattering or interference during exposure, the opening of the mask layer does not form a sidewall perpendicular to the substrate, and has a predetermined slope, In particular, the side wall is formed to gradually increase in width away from the substrate.

As a result, the electron emission portion also has a cross-sectional shape that increases in width away from the substrate, and the upper edge of the electron emission portion may be formed over the gate electrode without a separate surface activation process of removing the upper portion of the electron emission portion. This may cause a short circuit between the cathode electrode and the gate electrode.

On the other hand, when forming the electron emission portion by the screen printing method described above, further comprising a photosensitive material in the mixture, and using the mask layer as an exposure mask, the mixture filled in the opening of the mask layer with ultraviolet rays irradiated from the back surface of the substrate to selectively The curing method may be applied.

In this case, the mask layer generally consists of a photoresist layer which is non-transparent to ultraviolet rays. However, since the photoresist layer having such characteristics is highly reactive with the mixture including the electron emission material, the side of the electron emission portion is irregular, and the pattern of the electron emission portion is lowered.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to improve the uniformity of the shape of the electron emission unit and to suppress the short circuit between the cathode electrode and the gate electrode by the electron emission unit in the manufacturing process. It is to provide a manufacturing method.

In order to achieve the above object, the present invention,

Cathode electrodes, an insulating layer, and gate electrodes are sequentially formed on the substrate, and respective openings are formed in the gate electrodes and the insulating layer, a mask layer is formed over the substrate, and then patterned to form an opening in the electron emission region formation region. Forming an electron emission portion by screen printing a mixture containing an electron emission material in the opening of the mask layer, and forming the mask layer to form a first mask layer that is impermeable to ultraviolet rays. After that, the patterning is performed to form an opening in the electron emission region forming region, and a second mask layer formed of a material having a low reactivity with the mixture is formed on the first mask layer and then patterned to form a first mask at the electron emission region forming region. Process of forming an opening having a sidewall perpendicular to the mask layer opening. To provide a crude method.

In the method of manufacturing the electron emission device, the substrate may be formed of a transparent substrate, and the cathode electrodes may be formed of a transparent conductive film.

In addition, the first mask layer may be formed of a photoresist layer, and the first mask layer may be developed after exposure to form a first mask layer opening from a rear surface of the substrate.

In addition, the second mask layer may be formed of any one of a light transmissive photoresist layer and a metal, and when the second mask layer is formed of a light transmissive photoresist layer, the second mask layer may be developed after exposure to the second mask layer. 2 mask layer openings can be formed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1A-1F are schematic diagrams at each manufacturing step shown to illustrate a method of manufacturing an electron emitting device according to an embodiment of the present invention.

Referring first to FIG. 1A, a conductive film is formed on a substrate 2 and patterned to form stripe cathode electrodes 4, and an insulating material is deposited on the entire substrate 2 over the cathode electrodes 4. Screen printing is performed to form the first insulating layer 6. A conductive film is formed on the first insulating layer 6 and patterned to form gate electrodes 8 having a stripe shape orthogonal to the cathode electrode 4. At this time, the intersection area between the cathode electrode 4 and the gate electrode 8 forms a unit pixel.

The substrate 2 and the cathode electrode 4 are formed of a transparent material for the back exposure process described below. That is, the substrate 2 is prepared as a transparent substrate, and the cathode electrode 4 is formed of a transparent conductive film such as indium tin oxide (ITO).

Subsequently, an insulating material is deposited or screen printed on the entire substrate 2 over the gate electrodes 8 to form a second insulating layer 10, and a conductive material is coated on the second insulating layer 10 to form the focusing electrode 12. ). In addition, the focus electrode 12, the second insulating layer 10, the gate electrode 8, and the first insulating layer 6 are sequentially etched to form the openings 14, thereby forming the cathode electrode in which the electron emission part is located. Expose some surface of 4).

In this case, since the second insulating layer 10 and the focusing electrode 12 are optional additions, only the cathode electrode 4, the first insulating layer 6, and the gate electrode 8 are formed on the first substrate 2. It is okay.

Next, as shown in FIG. 1B, the first mask layer 16 is formed on the entire substrate 2 and then patterned to expose a portion of the surface of the cathode electrode 4 at the electron emission region forming region ( 161 is formed. The first mask layer 16 may be formed of a photoresist layer. For example, the first mask layer 16 may be formed of a positive photoresist layer in which an exposed portion is dissolved and removed.

In the forming of the opening 161 in the first mask layer 16, the exposure mask 18 having the opening 181 is disposed on the back surface of the substrate 2 and the electron emission part forming portion is disposed on the substrate 2. The first mask layer 16 may be partially exposed by irradiating ultraviolet rays from the rear surface of the back panel), and the exposed portion may be removed by developing. At this time, the first mask layer opening 161 is exposed together with the unintentional portion by the scattering and interference of ultraviolet rays to form an inclined sidewall having a larger width as it moves away from the substrate 2.

The first mask layer 16 completed through the above process has a feature that does not transmit ultraviolet rays so that it can be used as an exposure mask in a later step of forming an electron emission unit.

Subsequently, as shown in FIG. 1C, the second mask layer 20 is formed over the substrate 2 and patterned to form the opening 201 at the electron emission region formation site.

In the present exemplary embodiment, the second mask layer 20 is formed of a material having a low reactivity with a mixture including an electron emission material in an electron emission portion forming step, and includes a light transmissive photoresist layer or a metal that transmits ultraviolet light. This includes.

When the second mask layer 20 is formed of a photoresist layer, forming the opening 201 in the second mask layer 20 may be performed by using the first mask layer 16 as an exposure mask without a separate exposure mask. The second mask layer 20 may be partially exposed by irradiating ultraviolet rays from the rear surface of the substrate 2 and may be formed by removing an exposed portion through development.

When the mask layer is formed in the second manner as described above, since the first mask layer 16 formed first suppresses scattering or interference of ultraviolet rays when the second mask layer 20 is exposed, the second mask layer 20 is formed of the first mask. An opening 201 of a sidewall perpendicular to the opening 161 of the first mask layer 16 is formed on the layer 16. That is, the second mask layer 20 is formed to have a larger thickness gradually away from the substrate 2 at the sidewall of the opening 161 of the first mask layer 16, so that the opening 161 of the first mask layer 16 is formed. The opening 201 of the more vertical sidewall is formed.

In FIG. 1C, reference numeral 22 denotes a mask layer including the first mask layer 16 and the second mask layer 20, and 221 denotes an opening of the mask layer 22. After the process, the mask layer 22 forms an opening 221 which is wider as it moves away from the substrate 2. However, the opening 221 is formed by the first mask layer 16 and the second mask layer 20. Since the verticality of the sidewalls is increased, a portion under the opening 221 where the electron emission portion will be formed later forms a substantially vertical sidewall.

Next, a mixture including an electron emission material is injected into the mask layer opening 221 to form an electron emission portion.

In forming the electron emission unit, ① a mixture of an electron emission material on a powder and an organic material such as a vehicle and a binder is prepared to produce a mixture having a viscosity suitable for printing, and ② the mixture is selectively printed on the opening 221 of the mask layer 22. And, ③ can be formed through the process of drying and baking the printed mixture.

On the other hand, referring to Figure 1d, ① the mixture of the electron-emitting material on the powder and organic materials such as vehicle, binder and photosensitive material to produce a mixture having a viscosity suitable for printing, ② the mixture (dotted line) on the mask layer 22 Screen printing), (3) irradiate ultraviolet rays through the back of the substrate (2) to selectively cure the mixture filled in the opening (221) of the mask layer (22), (4) remove the uncured mixture, and then dry and The electron emission part 24 may be formed through the baking process.

As the electron emission material, carbon nanotubes (CNT), graphite, graphite nanofibers, diamonds, diamond-like carbons (DLC), fullerenes (C ₆₀ ), silicon nanowires, or a combination thereof may be applied.

Subsequently, the mask layer 22 is removed, and the surface activation step of attaching the adhesive tape 26 to the entire structure provided on the substrate 2 as shown in FIG. 1E and removing the adhesive tape 26 from the structure is performed. Proceed. Through this step, the electron emitting portion 24 removes the upper surface layer to expose the electron emitting materials to the surface, and each electron emitting material is aligned in a direction perpendicular to the surface of the substrate 2 to expose its sharp ends. As a result, the electron emission efficiency can be doubled.

Through the above process, the electron emission device shown in FIG. 1F is completed.

As described above, according to the manufacturing method of the present exemplary embodiment, the electron emission parts 24 may have vertical sides with respect to the substrate 2 along the shape of the opening 221 of the mask layer 22, and the electron emission parts having high shape uniformity ( 24) can be easily formed. Therefore, the emission characteristic of each pixel can be made uniform, and the distance between the electron emission section 24 and the gate electrode 8 can be maintained uniformly, and short-circuit of the cathode electrode 4 and the gate electrode 8 can be prevented. have.

In addition, according to the manufacturing method of the present embodiment, since most of the sides of the electron emitting portion 24 are in contact with the second mask layer 20 having low reactivity with the mixture including the electron emitting material in the electron emitting portion 24 forming step. There is an effect of suppressing the deformation of the electron emitting portion 24 and increasing the pattern.

Hereinafter, a configuration of an electron emission display device using the electron emission device 100 manufactured by the above-described method will be described with reference to FIG. 2.

Referring to the drawings, the electron emission display device includes a first substrate 28 and a second substrate 30 which are arranged in parallel to each other at predetermined intervals. Sealing members (not shown) are disposed at the edges of the first substrate 28 and the second substrate 30 to bond the two substrates, and the internal space is evacuated with a vacuum of approximately 10 ⁻⁶ torr to allow the first substrate 28 to be bonded. ), The second substrate 30 and the sealing member constitute a vacuum container.

On the opposite surface of the first substrate 28 to the second substrate 30, electron emission elements are arranged in an array to form the electron emission device 100 together with the first substrate 28, and the electron emission device ( 100 is combined with the second substrate 30 and the light emitting unit 110 provided on the second substrate 30 to form an electron emission display device.

First, cathode electrodes 4, which are first electrodes, are formed on the first substrate 28 in a stripe pattern along one direction of the first substrate 28, and cover the cathode electrodes 4. 28, the first insulating layer 6 is formed in its entirety. Gate electrodes 8, which are second electrodes, are formed on the first insulating layer 6 in a stripe pattern along a direction orthogonal to the cathode electrodes 4.

An intersection area between the cathode electrodes 4 and the gate electrodes 8 constitutes one unit pixel, and electron emission parts 24 are formed in each unit pixel above the cathode electrode 4. In addition, openings 61 and 81 corresponding to the electron emission parts 24 are formed in the first insulating layer 6 and the gate electrodes 8 to expose the electron emission parts 24 on the first substrate 26. Be sure to

The electron emission unit 24 may be formed of materials emitting electrons when a electric field is applied in a vacuum, such as a carbon-based material or a nanometer (nm) size material. The electron emission unit 24 may include, for example, carbon nanotubes (CNT), graphite, graphite nanofibers, diamonds, diamond-like carbons (DLC), fullerenes (C ₆₀ ), silicon nanowires, or a combination thereof. have.

In the drawing, the circular electron emitters 24 are arranged in a line along the longitudinal direction of the cathode electrode 4, but the shape of the electron emitters 24, the number and arrangement form per pixel area, etc. are illustrated. It is not limited to the example and can be variously modified.

The focusing electrode 12, which is a third electrode, is formed on the gate electrodes 8 and the first insulating layer 6. A second insulating layer 10 is positioned below the focusing electrode 12 to insulate the gate electrodes 8 and the focusing electrode 12, and also passes the electron beam through the second insulating layer 10 and the focusing electrode 12. Openings 101 and 121 are provided. The openings 101 and 121 may be formed one for each electron emission part 24 or one for each unit pixel, and the second case is illustrated in the drawing.

Next, on one surface of the second substrate 30 opposite to the first substrate 28, the fluorescent layer 32, for example, the red, green, and blue fluorescent layers 32R, 32G, and 32B may be randomly selected from each other. It is formed at intervals, and a black layer 34 is formed between the fluorescent layers 32 to improve the contrast of the screen. The fluorescent layer 32 is disposed so that the fluorescent layers 32R, 32G, and 32B of one color correspond to the unit pixels set on the first substrate 28.

An anode electrode 36 made of a metal film such as aluminum (Al) is formed on the fluorescent layer 32 and the black layer 34. The anode 36 receives the high voltage necessary for accelerating the electron beam from the outside to maintain the fluorescent layer 32 in a high potential state, and the visible light emitted toward the first substrate 28 of the visible light emitted from the fluorescent layer 32. Is reflected toward the second substrate 30 to increase the brightness of the screen.

The anode electrode may be formed of a transparent conductive film such as ITO, in which case the anode electrode is positioned on one surface of the fluorescent layer 32 and the black layer 34 facing the second substrate 30. Moreover, the structure which forms simultaneously the above-mentioned transparent conductive film and a metal film as an anode electrode is also possible.

In addition, spacers 38 are disposed between the first substrate 28 and the second substrate 30 to support the compressive force applied to the vacuum container and to keep the distance between the two substrates constant. The spacers 38 are positioned corresponding to the black layer 34 so as not to invade the fluorescent layer 32.

The electron emission display device having the above-described configuration is driven by supplying a predetermined voltage to the cathode electrodes 4, the gate electrodes 8, the focusing electrode 12, and the anode electrode 36 from the outside.

For example, any one of the cathode electrodes 4 and the gate electrodes 8 receives a scan driving voltage to serve as scan electrodes, and the other electrodes receive a data driving voltage to serve as data electrodes. In addition, the focusing electrode 12 receives a voltage required for electron beam focusing, for example, 0 V or a negative DC voltage of several to several tens of volts, and the anode electrode 36 requires a voltage for accelerating the electron beam, for example, several hundred to several thousand volts. DC voltage of is applied.

Then, an electric field is formed around the electron emission unit 24 in the unit pixels in which the voltage difference between the cathode electrode 4 and the gate electrode 8 is greater than or equal to the threshold, and electrons are emitted therefrom. The emitted electrons are focused to the center of the electron beam bundle while passing through the opening 121 of the focusing electrode 12, and attracted by the high voltage applied to the anode electrode 36 to impinge on the fluorescent layer 32 of the corresponding unit pixel. It emits light.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

As described above, the method for manufacturing an electron emitting device according to the present invention further forms a second mask layer having a low reactivity with the electron emitting portion, thereby ensuring verticality of the electron emitting portion and increasing the pattern of the electron emitting portion to increase the pattern of the electron emitting portion. Improve shape uniformity and thus electron emission uniformity. In addition, the electron emission device according to the present invention can improve the shape of the electron emission portion to ensure a sufficient distance between the electron emission portion and the gate electrode, thereby preventing the short circuit between the cathode electrode and the gate electrode.

Claims (9)

Forming cathode electrodes, an insulating layer and a gate electrodes on the substrate in turn; Forming respective openings in the gate electrodes and the insulating layer; Forming a mask layer over the substrate and then patterning the mask layer to form an opening in an electron emission region forming portion; Screen printing a mixture containing an electron emitting material in the opening of the mask layer to form an electron emitting portion, Forming the mask layer, Forming a first mask layer that is impermeable to ultraviolet rays and patterning the first mask layer to form an opening in an electron emission region formation site; Forming a second mask layer formed of a material having less reactivity with the mixture on the first mask layer and then patterning the second mask layer to form an opening having a sidewall perpendicular to the opening of the first mask layer at an electron emission region forming region The manufacturing method of the electron emission device which consists of. The method of claim 1, And forming the substrate into a transparent substrate and forming the cathode electrodes into a transparent conductive film. The method of claim 1, Forming the first mask layer as a photoresist layer, And developing the first mask layer after exposure from the backside of the substrate to form a first mask layer opening. The method of claim 1, A method of manufacturing an electron emitting device, wherein the second mask layer is formed of any one of a light transmissive photoresist layer and a metal. The method of claim 1, The second mask layer is formed of a light transmissive photoresist layer, And developing the second mask layer after exposure from the back surface of the substrate to form a second mask layer opening. The method of claim 1, The electron emitting material includes at least one material selected from the group consisting of carbon nanotubes (CNT), graphite, graphite nanofibers, diamonds, diamond-like carbons (DLC), fullerenes (C ₆₀ ), and silicon nanowires. Method of Making a Release Device. The method of claim 1, Forming the electron emission portion, Preparing the mixture by mixing an electron emitting material with an organic and photosensitive material, screen printing the mixture on the mask layer, selectively curing the mixture filled in the openings of the mask layer by irradiating ultraviolet rays from the rear surface of the substrate, A method of making an electron emitting device comprising the steps of removing the uncured mixture. The method of claim 1, After forming the electron emitting portion, Attaching an adhesive tape over the structure provided on the substrate, and removing the adhesive tape from the structure to activate the surface of the electron emitting portion. The method of claim 1, Before forming the mask layer, Forming an additional insulating layer and a focusing electrode on the gate electrodes, and forming respective openings in the focusing electrode and the additional insulating layer.

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