JP2001195972A - Cold cathode and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold cathode and a manufacturing method of the same using a cylindrical electron source being orientation controlled. SOLUTION: A physical formed goods is provided at a fastening member of a cylindrical electron source and an orientation control assistant material is dispersed into a paste containing the cylindrical electron source, whereby it is possible to constitute a cold cathode from the cylindrical electron source being orientation controlled and to use a carbon nano-tube. This cold cathode is formed in the physical properties by the rubbing process, the oblique vapor- deposition process, or the whiskers process, and an electro emission area is formed by the silk-screen process or the spin coating process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode using an alignment-controlled cylindrical electron source and a method of manufacturing the same, and more particularly to a cold cathode lamp, a fluorescent display tube, a backlight for a liquid crystal device, The present invention relates to a cold cathode suitably used for a field emission display and a method for manufacturing the cold cathode.

[0002]

2. Description of the Related Art In recent years, electron sources that emit field emission electrons by applying a strong electric field have been actively researched and developed, and are expected to be applied to flat panel displays, that is, field emission displays (FED). ing.

On the other hand, a fluorescent display tube using carbon nanotubes has recently been announced. Carbon nanotubes have a shape in which graphite layers wound in a cylindrical shape are nested, and are described in Iijima et al. (S. Iijima, Natu
re, 354, 56, 1991).
A fluorescent display tube using such carbon nanotubes (FIG. 13) emits light with high luminance at a current density of about 10 A / cm ² , as disclosed in JP-A-11-111161, and is an excellent device. Show characteristics.

[0004]

However, in the fluorescent display tube disclosed in JP-A-11-111161, since the carbon nanotubes are fixed with a conductive adhesive, the carbon nanotubes are not sufficiently oriented. I didn't. For this reason, there is a problem that the luminance variation of the fluorescent display tube occurs in the light emitting surface.

[0005] In addition, oriented carbon nanotubes can be obtained by selective growth of carbon nanotubes on a metal surface, but there has been a problem that the production of the carbon nanotubes becomes difficult as the device becomes larger in area.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a cold cathode using a cylindrical electron source whose orientation is controlled, and a method of manufacturing the same.
In particular, the orientation control depending on the physical shape is performed, and the orientation control aid enhances the orientation force of the cylindrical electron source.

[0007]

In order to achieve the above object, a cold cathode according to the present invention has an electron source array for emitting electrons, a gate electrode for extracting electrons, and electrically connected to the electron source. In a cold cathode composed of a cathode electrode and a gate insulating layer that electrically insulates the gate electrode and the cathode electrode, the physical shape of the material surface to which the cylindrical electron source constituting the electron source array is fixed is fixed. It is characterized in that the orientation is controlled dependently.

Preferably, the physical shape is formed on an alignment film on the cathode electrode, and the alignment film has a current limiting mechanism. Further, the cylindrical electron source whose alignment is controlled is formed on a paste. The paste is dispersed, and the paste contains an orientation control aid.

The method of manufacturing a cold cathode according to the present invention comprises a step of forming a cathode electrode on a support substrate, a step of forming a physical shape on the cathode electrode, and a cylindrical electron source. Forming an electron emission region, forming a gate insulating layer, forming a gate electrode, and exposing the electron emission region by forming a gate opening.

Further, after the step of forming the cathode electrode on the supporting substrate, the method further includes a step of forming an alignment film on the cathode electrode, and a step of forming a physical shape on the alignment film. .

Preferably, the step of forming the physical shape is selected from any one of a rubbing method, an oblique deposition method, and whisker formation, and the formation of the electron emission region is performed by a screen printing method or a spin coating method. It is characterized by the law. With this configuration, the orientation can be easily controlled with the base shape by a force applied in the printing direction or some mechanical external force such as a centrifugal force applied outward.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> FIGS. 1 and 2
1 shows a cross-sectional view of a cold cathode according to the present embodiment and a perspective view of a field emission display using the cold cathode. Hereinafter, the basic structure of the cold cathode of the present embodiment will be described with reference to FIGS.

As shown in FIG. 1, a cathode electrode 2 is formed on a cathode support substrate 1, and an electron emission region (pixel portion) of the cathode electrode 2 has a physical shape for controlling the orientation of a cylindrical electron source. 3 are provided. As the cylindrical electron source in the present invention, CNT (carbon nanotube), BN (boron nitride) nanotube, metal whisker and the like can be used. This physical shape 3
Are formed by a rubbing method in FIG. By forming the physical shape by the rubbing method, a cold cathode having a large area can be easily formed at low cost.

As other methods of forming such a physical shape 3, there are a method of forming by an oblique evaporation method as shown in FIG. 3A and a method of forming a whisker as shown in FIG. 3B. is there. Here, whiskers are needle-shaped single crystals, and copper, iron, silver, nickel, cobalt, platinum, gold, and the like can be used. It is possible to use those produced by a condensation method, generation from a solid phase, an electrolytic deposition method, a thermal decomposition method, a VLS method, or the like.

By forming the physical shape 3 by oblique vapor deposition, a cold cathode having the physical shape 3 excellent in uniformity can be formed, and by forming the whisker, a high-definition cold cathode can be formed. Becomes possible.

In any case, when a person skilled in the art controls the orientation of a cylindrical electron source with each device, it is necessary to obtain a physical shape 3 corresponding to the design and appropriately select a manufacturing method corresponding to the shape. Is preferred.

The cylindrical electron source 4 shown in FIG. 1 is oriented in a direction perpendicular to the cathode support substrate 1 depending on such a physical shape 3. The cylindrical electron source 4 is divided into a desired pattern by the paste 5 and is fixed to the cathode electrode 2. On such a cylindrical electron source 4, a gate insulating layer 6 and a gate electrode 7 are sequentially deposited, and a gate opening 8 is formed in a desired electron emission region.

FIG. 2 is a perspective view in which such a cold cathode is used for a field emission display. A cathode electrode 2 is formed on a cathode support substrate 1, and a paste pattern 5 containing a cylindrical electron source 4 is formed on the cathode electrode 2.
Is provided. The paste pattern 5 is XY-address driven by the cathode electrode 2 and the gate electrode 7, and an emission current is emitted from the gate opening 8 corresponding to the addressed paste pattern 5. The emitted emission current is attracted to the anode electrode 9, collides with the phosphor 10 coated on the anode electrode 9, and the phosphor 1
0 emits light.

We have confirmed by SEM observation that the cylindrical electron source 4 can be controlled in orientation by providing the physical shape 3 on the cathode electrode 2. Further, it was confirmed by electrical evaluation that the use of the cylindrical electron source 4 whose orientation was controlled increased the emission current and improved the uniformity of the emission current.

Here, the method of manufacturing the cold cathode of this embodiment will be described below with reference to FIGS. 4 (a) to 4 (c) and FIGS. 5 (a) to 5 (b). First, as shown in FIG. 4A, a cathode electrode 2 is formed on a cathode support substrate 1, and a physical shape 3 for controlling orientation is formed. The physical shape 3 of the cathode electrode 2 is preferably used after appropriately selecting a method such as a rubbing method or an oblique vapor deposition method. However, when manufacturing by the oblique evaporation method, it is necessary to use a vacuum evaporation apparatus or the like, and therefore, there is a problem in terms of the apparatus for manufacturing a large-sized cold cathode.

Next, as shown in FIG. 4B, a paste pattern 5 containing the cylindrical electron source 4 is formed, and the cylindrical electron source 4 is oriented. The cylindrical electron source 4 is dispersed in paste such as frit glass, and the paste containing the cylindrical electron source 4 is screen-printed using a screen mask.

Here, how the cylindrical electron source 4 is oriented will be described with reference to FIGS. 6A and 6B in comparison with the conventional method. FIG. 6A is a cross-sectional process diagram when the paste 10 is screen-printed on a flat (conventional) cathode electrode 2, and FIG. 6B is a physical diagram of the cathode electrode 2 for controlling the orientation of the paste 10. The cross-sectional process drawing at the time of screen printing on target shape 3 is shown, respectively. The paste used at this time is preferably a paste of frit glass or the like. As shown in FIG. 6A, when the squeegee 11 is moved in the movement direction 12, the formation of the cylindrical electron source 4 in the paste pattern becomes random on the conventional flat cathode electrode 2.

On the other hand, as shown in FIG. 6B, the squeegee 11 is placed on the physical shape 3 of the cathode electrode 2 for controlling the orientation.
Is moved in the movement direction 12, the orientation of the cylindrical electron source 4 is controlled by the mechanical force accompanying the movement of the squeegee under the assistance of the physical shape 3. By such a mechanism, as shown in FIG. 4B, the arrangement of the cylindrical electron source 4 is controlled in the vertical direction with respect to the cathode electrode 2.

Further, it is possible to control the orientation of the cylindrical electron source 4 by a method different from the above method, and an example of the manufacturing method will be described below. The physical shape 3 for controlling the orientation is formed on the cathode electrode by a rubbing method or the like. The cylindrical electron source 4 is dispersed in a paste of an ultraviolet curing resin, an electron beam curing resin, a thermosetting resin or the like, and the paste is applied by a spin coater. The cylindrical electron source 4 is oriented not by the mechanical force accompanying the movement of the squeegee but by the mechanical force accompanying the rotation of the spin coater. Desired paste pattern 5
Are obtained by applying ultraviolet rays, electron beams, and infrared rays (heat) to cure respective resins.

Even when a resin is used, the physical shape is an important factor. That is, at the stage of application by a spin coater, there is a certain degree of viscosity, and the orientation is easily controlled by the centrifugal force and the physical shape of the substrate. Patterning is performed after the orientation is controlled. This is because it is fixed to the electrode.

Finally, a gate insulating layer 6 is deposited on the paste pattern 5 containing the cylindrical electron source 4 (FIG. 4).
(C)), the gate electrode 7 is formed (FIG. 5A), and the gate opening 8 is formed by removing the gate insulating layer 6 in the electron emission region. A cold cathode using the cylindrical electron source is obtained.

<Second Embodiment> FIG. 7 is a sectional view of a cold cathode according to a second embodiment of the present invention. Unlike the first embodiment, the orientation control aid 13 is included in the paste pattern 5. In the “groove” portion of the physical shape 3 for orientation control on the cathode electrode 2 described above, an orientation control assistant 13 is oriented, and the cylindrical electron source 4 is triggered by the orientation control assistant 13. Orient. As described above, by further dispersing the orientation control aid 13 in the paste containing the cylindrical electron source 4 to form the paste pattern 5, the orientation control of the cylindrical electron source 4 that is difficult to be oriented and has a small aspect ratio is performed. Becomes possible.

It is preferable that the orientation control aid 13 is larger than that of the cylindrical electron source. For example, when the diameter of the cylindrical electron source 4 is 30 nm and the length is 30 μm,
The size is about 10 times, that is, the diameter of the orientation control aid 13 is 3
The thickness is preferably about 00 nm and the length is about 300 μm. However, the size of the orientation control aid 13 is not limited to this, and experimental optimization is necessary depending on the type of the cylindrical electron source 4 and the paste.

As in the first embodiment, a cold cathode using a cylindrical electron source without orientation control is used.
The emission current and the uniformity of the emission current were improved.

Next, a method for manufacturing a cold cathode according to the second embodiment of the present invention will be described with reference to FIGS. 8 (a) and 8 (b) and FIGS.
This will be described below using (b). First, as in the first embodiment, a cathode electrode 2 is formed on a cathode support substrate 1, and a physical shape 3 for orientation control is formed on the cathode electrode 2. FIG. 8A is a cross-sectional process diagram when screen printing is performed on the physical shape 3 of the cathode electrode 2 for controlling the orientation of the paste 10. The paste 10 contains the cylindrical electron source 4 and the orientation control aid 13. When such a paste 10 is screen-printed (moving the squeegee 11 from left to right in the drawing on the paper) on the physical shape 3 for orientation control, the orientation control assistant 1
3 are oriented along the “groove”, and the oriented orientation control aid 1
3, the cylindrical electron source 4 controls the orientation.

When the paste 10 containing the cylindrical electron source 4 and the orientation control aid is screen-printed on the physical shape 3 for orientation control, as shown in FIG. The cylindrical electron source 4 in the paste 10 on the physical shape 3 is oriented. The orientation of the cylindrical electron source 4 in the region of the cathode electrode 2 other than the physical shape 3 is not different from the conventional one and is not preferable.

Next, as shown in FIG. 9A, a paste pattern 5 is formed by patterning the electron emission region (coinciding with the region of the physical shape 3 for controlling the alignment). In the present embodiment, a paste material for forming the paste 10 is preferably an organic material such as an ultraviolet curable resin, an electron beam curable resin, or a thermosetting resin. That is, paste pattern 5
Is patterned by performing ultraviolet irradiation, electron beam irradiation, and infrared irradiation (heat).

Finally, as shown in FIG. 9B, a gate insulating layer 6 and a gate electrode 7 are sequentially formed, and a gate opening 8 is formed, whereby a cold cathode according to the present embodiment is obtained.

<Third Embodiment> FIG. 10 shows the third embodiment of the present invention.
1 is a cross-sectional view of a cold cathode using a cylindrical electron source provided with an alignment film according to the embodiment. Unlike the first embodiment, the orientation control aid 13 is included in the paste pattern 5.

In the above-mentioned "groove" of the physical shape 3 for orientation control on the cathode electrode 2, an orientation control aid 13 is oriented, and the orientation control aid 13 is used as a trigger to form a cylindrical electron. Source 4 is oriented. It is preferable that such an orientation control aid 13 is manufactured according to the same specifications as in the second embodiment.

As in the first embodiment, the emission current and the uniformity of the emission current are improved for the cold cathode using the cylindrical electron source without orientation control.

Here, a method of manufacturing a cold cathode according to this embodiment will be described below with reference to FIGS. First, as shown in FIG. 11A, a cathode electrode 2 is formed on a cathode support substrate 1, and an alignment film 14 is formed. The physical shape 3 on the alignment film 14 is formed using a rubbing method. Such an orientation film 14 controls the orientation of the cylindrical electron source 4 and also functions to limit the emission current. Therefore, it is preferable that the alignment film 14 has a high resistance, and those skilled in the art, based on each device design,
Determine the resistance value.

Next, as shown in FIG.
The orientation of the cylindrical electron source 4 is controlled depending on the above physical shape 3. As in the first embodiment, the cylindrical electron source 4 includes:
It can be easily oriented by a screen printing method, a spin coating method or the like.

Finally, by forming the gate insulating layer 6 and the gate electrode 7, a cold cathode using a cylindrical electron source whose orientation is controlled as shown in FIG. 11C can be manufactured.

<Fourth Embodiment> In this embodiment, the focusing electrode 16 is provided on the cold cathode manufactured in the first to third embodiments.
To reduce the spot diameter of the electron beam. Here, a method for manufacturing a cold cathode according to the fourth embodiment of the present application will be described below with reference to FIGS.

First, the cathode electrode 2 is formed on the cathode support substrate 1 and the physical shape 3 for controlling the orientation is formed.
To form As described in the third embodiment, the alignment film 14 may be formed on the cathode electrode 2. Subsequently, as described with reference to FIG. 6, when the paste containing the cylindrical electron source 4 (which may contain the orientation control aid 13) is screen-printed, the cylindrical electron source shown in FIG. Source 4 can be fabricated with controlled orientation.

Next, a gate insulating layer 6 and a gate electrode 7 are formed. The formation of the gate insulating layer 6 and the gate electrode 7
4 (c) and FIGS. 5 (a) and 5 (b) of the first embodiment, but if there is room in the pitch of the gate electrode 7, the gate insulating layer 6 may be formed by screen printing. And the gate electrode 7 can be stacked.

Finally, the interlayer insulating layer 15 and the focusing electrode 16
To form The interlayer insulating layer 15 and the focusing electrode 16 are formed by stacking by a screen printing method. When the interlayer insulating layer 15 and the focusing electrode 16 are stacked in this manner, FIG.
As shown in (c), a cold cathode using the cylindrical electron source 4 having the orientation controlled and having the focusing electrode 16 can be manufactured.

[0044]

According to the present invention, it is possible to obtain a cold cathode in which a cylindrical electron source is oriented in a direction perpendicular to the cathode electrode by providing the cathode electrode with an uneven surface. Further, by providing the cold cathode with a current limiting mechanism, reliability can be improved.

According to a further aspect of the present invention, by dispersing the orientation control aid in the paste containing the cylindrical electron source, the orientation of the cylindrical electron source strongly depends on the orientation of the orientation control aid,
It has become possible to obtain a cold cathode whose orientation is controlled by a cylindrical electron source having a low aspect ratio. Further, when the cylindrical electron source is formed of carbon nanotubes, it is possible to provide a cold cathode using a material which can operate at a low vacuum and has improved ion impact resistance.

Further, according to the manufacturing method described in the present application, it is possible to improve the reliability of the cold cathode, and by forming the uneven shape by the rubbing method, it is possible to easily manufacture the cold cathode having a large area. By forming the cold cathode by the oblique deposition method, it is possible to provide a method of manufacturing a cold cathode having high uniformity. Further, by forming the cold cathode by using whiskers, it is possible to provide a method of manufacturing a cold cathode having high definition.

Further, by forming an electron emission region composed of a cylindrical electron source by a screen printing method or a spin coating method, a low-cost cold cathode using a cylindrical electron source whose orientation is controlled is used. A manufacturing method can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cold cathode according to a first embodiment.

FIG. 2 is a perspective view of a field emission display using the cold cathode according to the first embodiment.

FIG. 3A shows a physical shape formed by using an oblique deposition method, and FIG. 3B shows a physical shape formed by using a whisker.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of the cold cathode according to the first embodiment.

FIG. 5 is a cross-sectional view illustrating a manufacturing process of the cold cathode according to the first embodiment.

FIG. 6A is a cross-sectional process diagram when the paste is screen-printed on the flat portion of the cathode electrode, and FIG. 6B is a cross-sectional process diagram when the paste is screen-printed on the physical shape of the cathode electrode. It is.

FIG. 7 is a sectional view of a cold cathode according to a second embodiment.

FIG. 8 is a cross-sectional view illustrating a manufacturing process of the cold cathode according to the second embodiment.

FIG. 9 is a cross-sectional view illustrating a manufacturing process of the cold cathode according to the second embodiment.

FIG. 10 is a sectional view of a cold cathode according to a third embodiment.

FIG. 11 is a cross-sectional view illustrating a manufacturing process of the cold cathode according to the third embodiment.

FIG. 12 is a cross-sectional view illustrating a manufacturing process of the cold cathode according to the fourth embodiment.

FIG. 13 is a conventional fluorescent display tube using carbon nanotubes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cathode support substrate 2 Cathode electrode 3 Physical shape for orientation control 4 Cylindrical electron source 5 Paste 6 Gate insulating layer 7 Gate electrode 8 Electron emission area 9 Anode electrode 10 Phosphor 11 Squeegee 12 Screen mask 13 Alignment control aid 14 Alignment film 15 Interlayer insulating layer 16 Focusing electrode

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masao Urayama 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 5C031 DD17 DD19 5C036 EE01 EE14 EF01 EF06 EF09 EG12 EH26

Claims (7)

[Claims] An electron source array that emits electrons, a gate electrode that extracts electrons, a cathode electrode that is electrically connected to the electron source, and a gate insulating layer that electrically insulates the gate electrode from the cathode electrode Wherein the orientation is controlled depending on the physical shape of the surface of the material to which the cylindrical electron source constituting the electron source array is fixed. 2. The cold cathode according to claim 1, wherein the physical shape is formed on an alignment film on the cathode electrode, and the alignment film has a current limiting mechanism. 3. The cold cathode according to claim 1, wherein the cylindrical electron source whose orientation is controlled is dispersed in a paste, and the paste contains an alignment control aid. 4. A step of forming a cathode electrode on a support substrate, a step of forming a physical shape on the cathode electrode, a step of forming an electron emission region composed of a cylindrical electron source, A method for manufacturing a cold cathode, comprising: a step of forming a layer; a step of forming a gate electrode; and a step of forming a gate opening to expose an electron emission region. 5. A method comprising: after forming a cathode electrode on a support substrate, forming an alignment film on the cathode electrode, and forming a physical shape on the alignment film. A method for producing a cold cathode according to claim 4. 6. The cooling method according to claim 4, wherein the step of forming the physical shape is selected from one of a rubbing method, an oblique vapor deposition method, and whisker formation. Manufacturing method of cathode. 7. The method of manufacturing a cold cathode according to claim 4, wherein the formation of the electron emission region is performed by a screen printing method or a spin coating method.