JP2001023513A - Manufacture for cold cathode field electron emission element and manufacture for cold cathode field electron emission display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly and easily form an electron emission electrode with high electron emission efficiency. SOLUTION: This manufacturing method for a field emission element comprises (a) a process of forming a cathode electrode 11 on a supporting body 10, (b) a process of forming an insulation layer 12 on the supporting body 10 containing the top of the cathode electrode 11, (c) a process of forming a gate electrode 13A on the insulation layer 12, (d) a process of forming an opening 14B exposing the cathode electrode 11 at the bottom in at least the insulation layer 12, (e) a process of forming an electron emission electrode 15 comprising fine particles 100 and having an almost cone shape reflecting a field strength distribution inside the opening 14B by providing the charged fine particles 100 from the top of the opening 14B to accumulate the fine particles 100 on the cathode electrode 11 in a condition where an electric potential difference is applied between the cathode electrode 11 and the gate electrode 13A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a cold cathode field emission device and a method for manufacturing a cold cathode field emission display device incorporating the cold cathode field emission device.

[0002]

2. Description of the Related Art When an electric field having a strength greater than a certain threshold is applied to a metal or semiconductor placed in a vacuum, the energy barrier on the surface of the metal or semiconductor is reduced. The number of electrons that can surmount is increased, and electrons are emitted into a vacuum even at room temperature. Electron emission based on such a principle is called cold cathode field emission or simply field emission (field emission). 2. Description of the Related Art In recent years, a flat-type cold-cathode field-emission display device that applies the principle of field emission to image display, a so-called field emission display (FED), has advantages such as high brightness and low power consumption. Therefore, it is expected as an image display device which replaces a conventional cathode ray tube (CRT).

[0003] A cold cathode field emission display (hereinafter sometimes simply referred to as a display) generally includes a cathode panel having an electron emission region corresponding to each pixel arranged in a two-dimensional matrix. And an anode panel having a phosphor layer that emits light when excited by collision with electrons emitted from the electron emission region, and is disposed to face through a high vacuum layer. In each electron emission region on the cathode panel, usually, a plurality of electron emission electrodes are formed, and further, a gate electrode for extracting electrons from the electron emission electrodes is formed. The portion having the electron emission electrode and the gate electrode is a cold cathode field emission device, and is hereinafter simply referred to as a field emission device.

In order to obtain a large emission electron current at a low driving voltage in the structure of such a display device, for example, the tip of an electron emission electrode constituting a field emission element is formed to have a sharp pointed shape, It is necessary to reduce the size of the electron emission electrode to increase the density of the electron emission electrode in the electron emission region corresponding to one pixel, and to shorten the distance between the tip of the electron emission electrode and the gate electrode. Therefore, in order to realize these, field emission devices having various configurations have been conventionally proposed.

As a typical example of such a conventional field emission device, a so-called Spindt type field emission device (hereinafter, referred to as a Spindt type device) in which an electron emission electrode is formed of a conical conductor is known. Have been. An outline of a method for manufacturing a Spindt-type element will be described below with reference to FIGS. This manufacturing method is basically a method in which the conical electron emission electrode 55 is formed by vertical vapor deposition of a metal material. That is, the vapor deposition particles enter the opening 54 perpendicularly, but reach the bottom of the opening 54 by utilizing the shielding effect of the overhang-like deposit formed at the opening end of the opening 54. The amount of the vapor-deposited particles is gradually reduced, and the electron emission electrodes 55 made of conical deposits are formed in a self-aligned manner. Here, in order to facilitate removal of unnecessary overhang-like deposits, a release layer 56 is formed on the gate electrode 53.
Will be described in advance.

[Step-10] First, as shown in FIG. 9A, a cathode electrode 51 made of niobium (Nb) is formed on a support 50 made of, for example, a glass substrate, and then SiO ₂ is formed thereon. An insulating layer 52 made of a conductive material and a gate electrode 53 made of a conductive material are sequentially formed.
3 and insulating layer 52 are patterned to form openings 5.
4 is formed. This patterning includes forming a resist mask (not shown) by ordinary photolithography,
Dry etching is performed through this resist mask.

[Step-20] Next, as shown in FIG. 9B, a release layer 56 is formed by obliquely depositing aluminum on the support 50. At this time, the peeling layer 56 is formed on the gate electrode 53 without substantially depositing aluminum on the bottom of the opening 54 by selecting a sufficiently large incident angle of the deposition particles with respect to the normal line of the support 50. be able to. The release layer 56 projects from the opening end of the opening 54 in an eaves-like manner, whereby the diameter of the opening 54 is substantially reduced.

[Step-30] Next, for example, molybdenum (Mo) is vertically deposited on the entire surface. At this time, as shown in FIG. 10A, as the conductive material layer 55A having the overhang shape grows on the separation layer 56, the substantial diameter of the opening 54 is gradually reduced. Part 5
The deposition particles contributing to the deposition at the bottom of 4 gradually become limited to those passing near the center of the opening 54. As a result, a conical deposit is formed at the bottom of the opening 54, and the conical deposit becomes the electron emission electrode 55.

[Step-40] Thereafter, as shown in FIG. 10B, the separation layer 56 is separated from the surface of the gate electrode 53 by an electrochemical process and a wet process, and a conductive material above the gate electrode 53 is formed. The layer 55A is selectively removed.

[0010]

The electron emission characteristic of the field emission device having the structure shown in FIG. 10B is such that the electron emission from the edge 53A of the gate electrode 53 forming the upper end of the opening 54 is performed. It largely depends on the distance to the tip of the electrode 55. This distance is usually on the order of submicron, and the processing accuracy and the dimensional accuracy of the diameter of the shape of the opening 54 and the conductive material layer 55 formed in [Step-30].
It largely depends on the film thickness accuracy of A, and further on the shape accuracy of the release layer 56 serving as the base. However, in practice, the conductive material layer 55 having a uniform film thickness over a large-area support is provided.
It is extremely difficult to form A by vertical vapor deposition or to form the peeling layer 56 having a uniform eaves shape by oblique vapor deposition, and some in-plane variation and variation between lots cannot be avoided. This variation causes variation in image display characteristics of the display device, for example, brightness of an image. In addition, a large deposition apparatus is required, the throughput is reduced, and when removing the release layer 56 formed over a large area, the residue causes contamination of the cathode panel, and the There is also a problem that the production yield of the device is reduced.

Accordingly, the present invention provides a method of manufacturing a cold cathode field emission device capable of uniformly and easily forming an electron emission electrode having a high electron emission efficiency, and a cold cathode field emission device incorporating such a cold cathode field emission device. An object of the present invention is to provide a method of manufacturing a cathode field emission display.

[0012]

To achieve the above object, a method of manufacturing a cold cathode field emission device (hereinafter abbreviated as "field emission device") according to the present invention comprises the steps of (a) forming a cathode electrode on a support; Forming, (b) forming an insulating layer on a support including on the cathode electrode, (c) forming a gate electrode on the insulating layer, and (d) exposing the cathode electrode at the bottom. Forming an opening at least in the insulating layer; and (e) supplying a charged powder from above the opening in a state where a potential difference is applied between the cathode electrode and the gate electrode, and supplying the charged powder onto the cathode electrode. Depositing a powder, thereby forming an electron emission electrode having a substantially conical shape reflecting the electric field intensity distribution in the opening.

Further, a method of manufacturing a cold cathode field emission display (hereinafter, abbreviated as a display) of the present invention for achieving the above object is a method of manufacturing a display incorporating the above-described field emission element. is there. That is, the substrate on which the anode electrode and the phosphor layer are formed, and the support on which the field emission device is formed are arranged so that the phosphor layer and the field emission device face each other, and the substrate and the support are disposed. A method for manufacturing a display device in which a body and a body are bonded at a peripheral portion, wherein each of the field emission devices includes:
(A) forming a cathode electrode on the support;
(B) forming an insulating layer on the support including the cathode electrode, (c) forming a gate electrode on the insulating layer, and (d) opening the cathode electrode at the bottom at least. Forming the insulating layer, and (e) supplying a charged powder from above the opening in a state where a potential difference is applied between the cathode electrode and the gate electrode to deposit the powder on the cathode electrode. The method is characterized by being manufactured through a step of forming an electron emission electrode made of the powder and having a substantially conical shape reflecting the electric field intensity distribution in the opening.

A method for manufacturing a field emission device and a method for manufacturing a display device according to the present invention (hereinafter, may be collectively referred to as the present invention).
In the above, the polarity of the charged powder is the same as the polarity of the gate electrode in the step (e), and can be opposite to the polarity of the cathode electrode in the step (e). By selecting the polarity in this manner, the adhesion of the powder to the surface of the gate electrode is prevented by the electric repulsion, and the adhesion of the powder to the cathode electrode is promoted by the electric attraction. Therefore, possible combinations of polarities are (1) powder / gate electrode / cathode electrode = negative / negative / positive, or (2) powder /
Gate electrode / cathode electrode = positive / positive / negative. However, in the combination of the above (1), the polarity of the cathode electrode, which is the polarity of the gate electrode, is opposite to the polarity during the actual operation of the field emission device or the display device. The reason why the polarity of the gate electrode and the polarity of the cathode electrode are referred to as “in the process (e)” is to clarify the distinction between the polarity during actual operation. In the present invention, in order to provide a stable potential difference between the cathode electrode and the anode electrode,
It is particularly preferable that the cathode electrode is grounded and the combination of (1) is employed.

In the present invention, the deposit of the powder formed on the cathode electrode becomes the electron emission electrode. The point that the shape of the electron emission electrode is controlled in a self-aligned manner according to the electric field intensity distribution in the opening. This is one of the advantages of the present invention. That is,
In the configuration of the Spindt-type field emission device or the field emission device based on the same operation principle as the Spindt type, the gate electrode is located at the upper end of the opening, and the cathode electrode is exposed at the bottom of the opening, In the opening, an electric field intensity distribution occurs according to the potential difference between the two electrodes and the shape of the opening.
The electric field intensity is lowest near the center of the opening, and increases as the distance from the center to the periphery increases. Since the charged powder concentrates more in a portion where the electric field intensity is lower, a substantially cone-shaped deposit (that is, an electron emission electrode) having a peak near the center of the opening is formed. Here, the “substantially conical shape” includes not only a normal conical shape but also a shape in which a normal conical side surface slightly swells outward or a side surface is slightly depressed inward. If the opening is circular, the shape of the electron emission electrode is substantially conical, and if the opening is n-shaped, the shape of the electron emission electrode is substantially n-pyramidal. still,
When the opening is rectangular, the electron-emitting electrode is a ridge with a ridge extending along the long side of the rectangle. In the present invention, the shape of the electron-emitting electrode is also included in the “substantially conical shape”. Shall be.

The powder deposit formed on the cathode electrode as described above can be put to practical use as an electron-emitting electrode as long as it has sufficient mechanical strength and stable electrical characteristics. However, when the mechanical strength and the stability of the electrical characteristics are insufficient, it is particularly preferable to provide (f) a step of firing the electron emission electrode after the step (e). The firing temperature is a temperature at which the heat resistance of the gate electrode, the cathode electrode, and the gate electrode can be sufficiently ensured. The firing atmosphere is such that the electrical resistivity of the gate electrode or the cathode electrode increases due to oxidation, or the gate electrode or the cathode electrode is heated. It is particularly preferable to use an inert gas atmosphere so as not to be removed by combustion.

Since the powder used in the present invention is a constituent material of the electron emission electrode, it is necessary that all or part of the constituent components have conductivity. A conductive substance is generally not charged in a bulk state, but does not leak in a state in which the powder is suspended in the air as a powder, so even if the entire constituent of the powder has conductivity. It is possible to supply charged powder. Examples of the conductive powder include carbon, tungsten (W), niobium (Nb),
Tantalum (Ta), titanium (Ti), molybdenum (M
o), high melting point metal such as chromium (Cr), or ITO
Powder of a transparent conductive material such as (indium / tin oxide) can be used.

On the other hand, the powder having a part of constituents having conductivity is, for example, a powder in which conductive particles are covered with a coating of a binder (binder). In the case where an electron-emitting electrode having excellent mechanical strength and electrical stability is formed by the above-described firing, it is extremely preferable to use such a powder. The powder having the binder coating can be handled in the same manner as the powder coating usually used in the field of electrostatic powder coating. As the conductive particles forming the core of the powder, the powder having the above-described conductivity can be used. A general-purpose resin can be used as the binder. The binder may be burned and removed by baking, or may remain in the gaps between the particles made of the conductive substance in a carbonized state and contribute to the adhesion between the particles. However, a general-purpose resin having an extremely high degree of polymerization or an extremely large multiple bond content requires a high temperature for firing, which may adversely affect the cathode electrode, the insulating layer, and the gate electrode during firing. Therefore, it is preferable to select a general-purpose resin that can be burned or carbonized at a temperature at which there is no risk of adverse effects on them. As such a general-purpose resin, a thermoplastic resin or a thermosetting resin can be used. Examples of the thermoplastic resin include a vinyl chloride resin, a polyolefin resin, a polyamide resin, a cellulose ester resin, and a fluorine resin. Examples of the thermosetting resin include an epoxy resin, an acrylic resin, and a polyester resin.
The shape of the powder is not particularly limited, and may be spherical, plate-like, needle-like, column-like, polyhedral, or irregular, but a shape that can increase the packing density of the powder in the sediment is particularly preferable.

Examples of the method of charging the powder and the apparatus used for supplying the powder include methods and apparatuses generally used in the field of electrostatic powder coating. Examples of the charging method include charging by contact / friction between powders, charging by collision with an obstacle, charging by electrostatic induction, and charging by collision with charged particles or electrons. Although each charging method may be employed alone, a plurality of charging methods are often involved in the process of charging the powder in a commonly used apparatus. Among them, a typical charging method is charging by collision with charged particles, and the charged particles are usually ions generated by corona discharge by an electrostatic powder spray gun. Electrostatic powder spray guns utilizing corona discharge include monopolar external charging type, monopolar internal and external charging type, monopolar internal charging type, bipolar external charging type, etc., all of which are used in the present invention. can do. In addition, a triboelectric type electrostatic powder spray gun is also known and can be used in the present invention.

In the present invention, since the polarity of the gate electrode and that of the powder during the powder supply in the step (e) are the same, the deposition of the powder on the gate electrode is prevented by the electric repulsion. Depending on the pattern shape and dimensions of the gate electrodes, the gate electrodes may be short-circuited by powder deposited in the space between adjacent gate electrodes. Therefore, in order to prevent this short circuit, in the step (e), it is particularly preferable to supply the powder with at least the protective layer formed on the insulating layer, and to remove the protective layer after forming the electron emission electrode. . The protective layer may be formed only over the insulating layer, or may be formed over the entire surface (that is, over the insulating layer including over the gate electrode).

It is required that the material and thickness of the protective layer do not substantially affect the electric field intensity distribution in the opening. An organic polymer material layer such as a photoresist layer usually used in the field of manufacturing semiconductor devices is suitable as a protective layer. The protective layer is formed, for example, in step (d)
After the formation of the opening is completed, a thin photoresist layer can be formed on the entire surface by spin coating, and the photoresist layer can be selectively removed at a portion of the bottom of the opening on the cathode electrode. . Alternatively, a protective layer that blocks a space between adjacent gate electrodes may be formed by, for example, a printing method. Further alternatively, if a photoresist material layer is used as an etching mask when forming an opening in the insulating layer in the step (d), and the remaining thickness of the photoresist layer after the etching is sufficiently small, The photoresist layer can be used as it is as a protective layer.

The cathode of the field emission device and the display device manufactured according to the present invention is made of tungsten (W), niobium (Nb), tantalum (Ta), titanium (Ti), molybdenum (Mo), chromium (Cr), or the like. And a transparent conductive material such as a high melting point metal, carbon, or ITO (indium tin oxide). The gate electrodes of the field emission device and the display device manufactured according to the present invention are made of tungsten (W), niobium (Nb), tantalum (Ta), titanium (Ti), molybdenum (Mo), chromium (Cr), and aluminum (Al). ), Copper (Cu), silver (Au) or the like, an alloy layer containing these metal elements, or a compound containing these metal elements (for example, Ti
Nitrides such as N, WSi ₂ , MoSi ₂ , TiSi ₂ , T
It can be formed using a semiconductor layer such as a silicide such as aSi ₂ ), silicon containing impurities, or a transparent conductive material such as carbon or ITO (indium tin oxide). Further, the constituent material of the anode electrode of the display device manufactured according to the present invention is selected according to the configuration of the display device. That is, when the display device is a transmissive type and the anode electrode and the phosphor layer are laminated on the substrate in this order, the anode electrode itself is transparent as well as the substrate on which the anode electrode is formed. It is necessary to use a transparent conductive material such as ITO (indium tin oxide). On the other hand, if the display device is of a reflective type, and even if it is of a transmissive type, a phosphor layer and an anode electrode are laminated in this order on a substrate, the display device may be associated with a cathode electrode or a gate electrode in addition to ITO. Then, the above-described materials can be appropriately selected and used.

The formation of the cathode electrode, the gate electrode, and the anode electrode is performed by a CVD method, a vapor deposition method,
Known processes such as a coating method, a sputtering method, and a printing method can be applied. In the CVD method, the vapor deposition method, the coating method, and the sputtering method, the entire surface of a material layer forming a cathode electrode or a gate electrode is formed. However, in the case where a release layer for lift-off is formed in advance on a film formation target. By removing the release layer, the cathode electrode and the gate electrode can be formed in a predetermined pattern. When the release layer is not formed, patterning by photolithography and etching can be performed. In a printing method such as a screen printing method, a final pattern of a cathode electrode and a gate electrode can be obtained in a single step. In particular, regarding a gate electrode, if there is a margin in dimensional accuracy, an opening is formed from the beginning. The gate electrode may be formed only by a printing method. Regarding the formation of the opening in the step (d), the expression that the opening is formed “at least” in the insulating layer is as follows.
This is because the opening may be formed at the same time by the printing method as described above, so that the opening in the gate electrode in the step (d) is not necessarily required.

The constituent material of the insulating layer is SiO ₂ , S
iN, SiON, or a cured glass paste can be used alone or appropriately laminated. For forming the insulating layer, a known process such as a CVD method, a coating method, a sputtering method, or a printing method can be used depending on a constituent material.

As the substrate on which the anode electrode is formed,
Examples include a glass substrate, a glass substrate having an insulating layer formed on its surface, a quartz substrate, and a quartz substrate having an insulating layer formed on its surface. In addition, the support on which the cathode electrode is formed only needs to have at least a surface formed of an insulating member, and a glass substrate, a glass substrate having an insulating layer formed on the surface, a quartz substrate, and an insulating layer formed on the surface. And a semiconductor substrate having an insulating film formed on its surface.

When a display device is manufactured by bonding a substrate on which an anode electrode and a phosphor layer are formed and a support on which a cold cathode field emission device is formed at a peripheral portion, the peripheral portion is made of only frit glass. It may be bonded, or may be bonded via a frame. The space between the bonded substrate and the support is approximately 10 ^-2
On the order of Pa or higher (ie, lower pressure)
Is maintained at a vacuum degree. When the frame is used, the adhesion between the frame and the substrate and the adhesion between the frame and the support can be performed using frit glass or a low-melting metal material.
The “low melting point” of the low melting point metal material is approximately 400 ° C.
The material can be appropriately selected from indium, indium-based alloy, tin-based solder, lead-based solder, and zinc-based solder. Such a low-melting-point metal material is less likely to degas compared to frit glass, so that the degree of vacuum in the space surrounded by the frame, the support, and the substrate is maintained for a long time, thereby extending the life of the display device. It is suitable for achieving.

In the present invention, when the field emission device further includes a focusing electrode, and the focusing electrode is formed at the upper end of the opening corresponding to each electron emission electrode, the cathode Instead of giving a potential difference between the electrode and the gate electrode, in a state where a potential difference is given between the cathode electrode and the focusing electrode, the charged powder is supplied from above the opening to supply the powder on the cathode electrode. Can also be deposited. The converging electrode is an electrode that generates an electric field for converging the electron trajectory so that electrons that jump out of the opening and travel toward the anode electrode enter only the desired phosphor layer. When a focusing electrode is provided, usually, a second insulating layer is further formed on the insulating layer including the gate electrode, a focusing electrode is formed on the second insulating layer, and at least the second insulating layer has
A second opening communicating with the opening is formed. The combination of the cathode electrode, the focusing electrode, and the polarity of the powder during powder supply is as described above.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings based on embodiments of the present invention (hereinafter, abbreviated as embodiments).

Embodiment 1 Embodiment 1 relates to a method of manufacturing a field emission device of the present invention and a method of manufacturing a display device of the present invention. FIG. 1 is a process diagram of a method for manufacturing a field emission device.
FIG. 3 to FIG. 3 show a conceptual configuration diagram of an electrostatic powder spraying device for forming an electron emission electrode. FIG. 4 shows that a substantially conical electron emission electrode is self-aligned by supplying charged powder. FIG. 5 conceptually shows a state in which such a field emission device is formed, and FIG. 6 shows a conceptual configuration diagram of a display device incorporating such a field emission device.

[Step-100] First, a cathode electrode 11 is formed on a support 10 made of, for example, a glass substrate. The cathode electrode 11 can be formed, for example, by forming a tungsten film entirely on the support 10 and then patterning the tungsten film. The cathode electrode 11 is not limited to a single material layer, but may be formed by stacking a plurality of material layers. For example, the surface layer of the cathode electrode 11 is made of a material having a higher electrical resistivity than the rest in order to cover variations in the electron emission characteristics of each electron emission electrode (reference numeral 15 in FIG. 2) formed in a later step. be able to. Next, the insulating layer 12 is formed on the support 10 including the cathode electrode 11. Here, as an example,
The paste is printed on the entire surface to a thickness of about 5 μm. Next, the insulating layer 12 is dried at, for example, 150 ° C. in order to remove moisture and a solvent contained in the insulating layer 12 and to flatten the insulating layer 12. In place of printing using the glass paste as described above, for example, S
Of course, an iO ₂ film may be formed.

Next, a gate electrode 13 is formed on the insulating layer 12. The gate electrode 13 can be formed, for example, by forming a tungsten film on the entire surface of the insulating layer 12 and then patterning the tungsten film. The extending direction of the stripe at this time is a direction orthogonal to the cathode electrode 11. (A-1) of FIG. 1 shows the gate electrode 13 on which only the stripe patterning has been performed.
-2) a gate electrode 13A in which an opening is patterned simultaneously in a region overlapping with the cathode electrode 11;
Is shown.

[Step-110] Next, as shown in FIG. 2A, etching is performed through an etching mask 16 made of, for example, a photoresist material. Here, the state at the end of [Step-100] is shown in FIG.
In the case shown in FIG. 1A, both the gate electrode 13 and the insulating layer 12 are etched, and the state at the end of [Step-100] is the state shown in FIG. 1A-2. Next, only the insulating layer 12 is etched. In any case, this etching forms an opening 14A with the cathode electrode 11 exposed at the bottom. Here, as an example, the opening 14A having a vertical wall is formed by anisotropic dry etching using a fluorine-based gas.

[Step-120] Next, isotropic etching is performed to retreat the side wall surface of the insulating layer 12 forming the opening 14A, as shown in FIG.
To form The isotropic etching can be performed by dry etching using radicals as a main etching species, such as chemical dry etching, or wet etching using an etchant. As an etchant, 49% hydrofluoric acid and pure water 1: 100
(Volume ratio) A mixed solution can be used. Further, as shown in FIG. 2C, the etching mask 16 is removed. The substrate (general term for the substrate 10, the cathode electrode 11, the insulating layer 12, and the gate electrode 13A) on which the processes up to this point have been completed is the object to be subjected to electrostatic powder spraying in the next step.

[Step-130] Next, as shown in FIG. 3, an electron emission electrode 15 having a substantially conical shape is formed on the cathode electrode 11. FIG. 3B is a schematic perspective view showing a part of the field emission device, and FIG. 3A is a sectional view taken along line AA of FIG. 3B. In FIG. 3B, the insulating layer 1 is formed so that the entire electron emission electrode 15 can be seen.
2 and a part of the gate electrode 13A are broken. FIG. 3 shows the cathode electrode 11 and the gate electrode 1 for simplification.
Although a state in which only one electron emission electrode 15 is formed in each overlapping region with 3A is illustrated, in the actual configuration of the field emission device, the number of pairs of the opening 14B and the electron emitting electrode 15 is several in each overlapping region. It is formed in an order of ten to several thousands, and is formed by an aggregate of the plurality of electron-emitting electrodes 15.
In many cases, an electron emission region corresponding to a pixel is configured.

Here, the configuration of the electrostatic powder spraying device for forming the electron emission electrode 15 will be described with reference to FIG. This device is roughly classified into a powder supply system, a powder spraying system, and a powder recovery system. The powder supply system mainly includes a powder supply pipe 24 for feeding the powder 100 to the electrostatic powder spray gun 26 with compressed air, and a hopper 23 connected to the powder supply pipe 24 for storing the powder. It is a component.
The powder 100 stored in the hopper 23 is a new powder,
It is a mixture with the powder recovered from a powder recovery system described below. The reason why the powder supply tube 24 is partially bent is to promote charging of the powder 100 by collision with the tube wall.

The powder spraying system includes an electrostatic powder spraying gun 2
6 and the spray booth 20 are main components. The electrostatic powder spray gun 26 is connected to the powder supply pipe 24 and has a cylindrical body 27 made of a rigid insulator such as an epoxy resin.
And a corona electrode 28 connected to a DC high-voltage power supply 25. The voltage applied by the DC high-voltage power supply 25 is usually about -30 to -90 kV.
The electrostatic powder spray gun 26 shown in FIG. 4 is a so-called monopolar externally charged gun, and the powder 100 conveyed by the compressed air flow is charged in a space in front of and near the corona electrode 28. . The spray booth 20 is a container for accommodating the object to be processed. A window is provided on the side wall surface, and the powder 100 charged from the electrostatic powder spray gun 26 is supplied through the window to the inside of the spray booth 20. Supplied to The spray booth 20 is shown in FIG.
The object to be processed is suspended in a hanger (not shown) while the spray booth 20 is
Is transported in a direction perpendicular to the plane of the drawing. Spray booth 20
The bottom is inclined so as to descend toward the center, thereby facilitating the recovery of the powder 100 that has not been deposited on the object.

The main components of the powder recovery system are an exhaust duct 21 connected to the bottom of the spray booth 20 and a recovery device 22 connected to the exhaust duct 21. In the recovery device 22, the powder 100 is collected using a cyclone and a filter.
Is collected. The collected powder 100 is returned to the hopper 23.

In order to form the electron emission electrode 15 using such an electrostatic powder spraying apparatus, as shown in FIG. 4, the support 10 is suspended in the spray booth 20 and the cathode electrode 11 is formed.
To ground. In this state, the cathode electrode 11 serves as an anode, and serves as a ground electrode opposite to the corona electrode 28 to which a high voltage is applied. Further, in the present invention, the gate electrode 13A is connected to the DC power supply 29 to have a negative potential. Electrostatic powder spray gun 26
The negatively charged powder 100 released from the substrate is attracted to the cathode electrode 11 as shown in FIG. At this time,
The powder 100 concentrates more in the vicinity of the center of the opening 14B having a low electric field intensity. As a result, as shown in the figure,
A substantially conical electron emission electrode 15 is formed. Note that FIG.
FIGS. 5 and 6 illustrate the “substantially conical” electron emission electrode 15 whose side surface is curved more inward than a normal cone. However, the shape of the electron emission electrode 15 is not necessarily the illustrated shape. Not limited.

In the first embodiment, as an example, carbon particles coated with a binder resin are used as powder 100,
The electron emission electrode 15 formed as described above is fired. Since this firing is performed in an inert gas atmosphere, there is no fear that the cathode electrode 11 and the gate electrode 13A made of tungsten are oxidized and the electrical resistivity increases. Also, the firing temperature is set to a temperature that does not adversely affect each part of the substrate already formed. By this firing, an electron emission electrode 15 having excellent mechanical strength and stability of electrical characteristics can be obtained.

In order to manufacture a display device, the support 10 on which the above-described field emission device is formed and the substrate on which the anode electrode and the phosphor layer are formed are combined with the phosphor layer and the field emission device. Are arranged so as to face each other, and the substrate and the support 10 are bonded to each other at the peripheral portion. Here, the support 10 on which the field emission devices are formed is referred to as a cathode panel CP, and the substrate on which the anode electrode and the phosphor layer are formed is referred to as an anode panel AP. Specifically, a frame (not shown) having a height of about 1 mm made of ceramics or glass was prepared, and the frame, the anode panel AP, and the cathode panel CP were temporarily bonded using frit glass. Thereafter, it may be fired at about 450 ° C. for 10 to 30 minutes. Thereafter, the inside of the display device is evacuated to a degree of vacuum of about 10 ⁻⁴ Pa and sealed by an appropriate method. Or,
The frame, the anode panel AP, and the cathode panel CP may be bonded together using a frit glass in a vacuum chamber,
In this case, since the inside of the display device is evacuated simultaneously with the bonding, exhaust in a later step is not required.

The display device thus obtained is shown in FIG.
As shown in FIG. 1, the pixel is composed of a plurality of pixels. Each pixel includes a plurality of the above-described field emission devices, and an anode electrode 32 and a phosphor layer 31 provided on a substrate 30 so as to face each other. The anode electrode 32 is made of, for example, aluminum, and is formed so as to cover the phosphor layer 31 formed in a predetermined pattern on a substrate 30 made of glass. The order of lamination of the phosphor layer 31 and the anode electrode 32 on the substrate 30 may be reversed, but in this case, the anode electrode 32 is located in front of the phosphor layer 31 when viewed from the observation surface side of the display device. Therefore, the anode electrode 32 must be made of a transparent conductive material such as ITO (indium tin oxide).

A relatively negative voltage is applied to the cathode electrode 11 from the scanning circuit 33, a relatively positive voltage is applied to the gate electrode 13A from the control circuit 34, and an anode electrode 32 is applied to the anode electrode 32 more than the gate electrode 13A. A higher positive voltage is applied from the acceleration power supply 35. When displaying on the display device, a video signal is input to the control circuit 34 and a scanning signal is input to the scanning circuit 33. Electrons e are extracted from the tip of the electron emission electrode 15 by an electric field generated when a voltage is applied to the cathode electrode 11 and the gate electrode 13. The electrons e are attracted to the anode electrode 32 and the phosphor layer 3
When it collides with 1, the phosphor layer 31 emits light, and a desired image can be obtained. In the display device of the present invention, since the tip of the electron emission electrode 15 is sharpened, the current efficiency, that is, the ratio of the anode current value to the cathode current value is also good.

(Embodiment 2) Embodiment 2 is a modification of Embodiment 1. The second embodiment is different from the first embodiment in that a protective layer is formed on the insulating layer 12 including the gate electrode 13A before spraying the electrostatic powder for forming the electron emission electrode 15. After the powder is supplied to form the electron emission electrode 15, the protective layer is removed. A method for manufacturing the field emission device according to the second embodiment will be described with reference to FIG. Note that the reference numerals in FIG. 7 are partially the same as those in FIG. 2, and a detailed description of the common portions will be omitted.

[Step-200] First, the steps up to the step of forming an opening 14A having a vertical wall in the insulating layer 12 by anisotropic etching are performed in the same manner as in [Step-100] of the first embodiment [FIG. (A).]. At this stage, the etching mask 16 formed on the insulating layer 12 including the gate electrode 13A can be used as it is as a protective layer in some cases.
6 has a large thickness, which may hinder the flight of the powder 100 in the next step of spraying the electrostatic powder and may affect the electric field intensity distribution in the opening 14A. Remove once. Then, as shown in FIG. 7A, the protective layer 17 is formed again. This protective layer 1
7 is formed, for example, by applying a photoresist material by a spin coating method and performing patterning to remove only the bottom portion of the opening 14A. still,
FIG. 7 shows a state in which the side wall surface of the opening 14A is also covered with the protective layer 17 as a result of allowing a margin for alignment when removing the protective layer 17 at the bottom of the opening 14A. The side wall surface of the opening 14A is not necessarily the protective layer 17
It does not need to be covered with. The protective layer 17 has an opening 14B whose side wall surface is recessed by isotropic etching.
May be formed after forming.

[Step-210] Next, electrostatic powder is sprayed in the same manner as in [Step-130] of the first embodiment, so that the surface of the cathode electrode 11 is formed as shown in FIG. The electron emission electrode 15 is formed.

[Step-220] Further, when the protective layer 17 is removed, a state shown in FIG. 7C is obtained. After that, if necessary, the insulating layer 12 is isotropically etched to retreat the side wall surface of the insulating layer 12 forming the opening 14A. Using the field emission device obtained in Embodiment 2, a display device can be further manufactured in the same manner as in Embodiment 1.

Although the present invention has been described based on the embodiments, the present invention is not limited to these embodiments. The details of the structure of the field emission device, the details of the processing conditions and the materials used in the method of manufacturing the field emission device, and the details of the structure of the display device to which the field emission device is applied are examples, and may be appropriately changed, selected, and combined. It is possible. For example, depending on the shape of the opening, an electron emission electrode having a different shape can be formed instead of the above-described substantially conical electron emission electrode 15. For example, as shown in FIG. 8, a cathode electrode 41, an insulating layer 42, a gate electrode 4
3 are sequentially formed, and when a plurality of (three in FIG. 3) rectangular openings 44 are formed in the gate electrode 43 and the insulating layer 42 in the overlapping region of the cathode electrode 41 and the gate electrode 43, On the exposed cathode electrode 11, an electron emission electrode 45 made of a ridge as shown can be formed by spraying the same electrostatic powder as described above.

[0048]

As is apparent from the above description, according to the method for manufacturing a field emission device of the present invention, an electron emission electrode having high electron emission efficiency can be formed uniformly and easily. Further, according to the method for manufacturing a display device of the present invention,
A display device having a highly uniform luminance distribution and image quality can be provided. Therefore, even if it is assumed that the display screen of the display device has a large area, it is possible to reduce the investment in manufacturing equipment, the process time, and the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a field emission device according to a first embodiment.

FIG. 2 is a process drawing illustrating a method for manufacturing the field emission device according to the first embodiment, following FIG. 1;

FIG. 3 is a process drawing illustrating a method for manufacturing the field emission device according to the first embodiment, following FIG. 2;

FIG. 4 is a conceptual configuration diagram of an electrostatic powder spraying device used in the present invention.

FIG. 5 is a principle diagram for conceptually explaining how a substantially conical electron emission electrode is formed in a self-aligned manner by supplying charged powder.

FIG. 6 is a partial end view conceptually showing a configuration example of a display device incorporating the above-mentioned field emission element.

FIG. 7 is a process chart showing a method of manufacturing the field emission device according to the second embodiment.

FIG. 8 is a schematic perspective view showing another example of the shape of the electron emission electrode.

FIG. 9 is a process chart showing a method for manufacturing a conventional Spindt-type field emission device.

FIG. 10 is a process drawing illustrating a method for manufacturing the conventional Spindt-type field emission device, following FIG. 9;

[Explanation of symbols]

10 ... Support, 11, 41 ... Cathode electrode, 1
2, 42 insulating layer, 13A, 43 gate electrode, 14A, 14B, 44 opening, 15, 45
..Electron emission electrodes, 17: protective layer, 30: substrate, 31: phosphor layer, 32: anode electrode, C
P: Cathode panel, AP: Anode panel

Claims (6)

[Claims] (A) forming a cathode electrode on a support; (b) forming an insulating layer on the support including the cathode electrode; and (c) forming a gate electrode on the insulating layer. Forming an opening having a cathode electrode exposed at the bottom at least in an insulating layer; and (e) providing a potential difference between the cathode electrode and the gate electrode. A charged powder is supplied from above to deposit the powder on the cathode electrode, and thus, an electron emission electrode made of the powder and having a substantially conical shape reflecting the electric field intensity distribution in the opening. Forming a cold cathode field emission device. 2. The method according to claim 1, wherein the polarity of the charged powder is the same as the polarity of the gate electrode in step (e) and opposite to the polarity of the cathode electrode in step (e). The method for manufacturing a cold cathode field emission device of the present invention. 3. The method for manufacturing a cold cathode field emission device according to claim 1, further comprising: (f) firing the electron emission electrode after the step (e). 4. The method according to claim 1, wherein, in the step (e), the powder is supplied while at least a protective layer is formed on the insulating layer, and the protective layer is removed after forming the electron emission electrode.
5. The method for manufacturing a cold cathode field emission device according to item 1. 5. The method according to claim 4, wherein an organic polymer material layer is used as the protective layer. 6. A substrate on which an anode electrode and a phosphor layer are formed, and a support on which a cold cathode field emission device is formed, such that the phosphor layer and the cold cathode field emission device face each other. And a method of manufacturing a cold cathode field emission display device in which the substrate and the support are adhered at a peripheral portion thereof, wherein each of the cold cathode field emission devices comprises: (a) a cathode electrode on the support; Forming; (b) forming an insulating layer on the support including on the cathode electrode; (c) forming a gate electrode on the insulating layer; and (d) exposing the cathode electrode at the bottom. Forming an opening at least in the insulating layer; and (e) supplying a charged powder from above the opening in a state in which a potential difference is applied between the cathode electrode and the gate electrode to form the opening on the cathode electrode. Depositing a powder, thus comprising said powder; The manufacturing method of a cold cathode field emission display characterized in that it is manufactured through the steps of forming an electron emission electrode having a substantially conical shape that reflects the electric field intensity distribution in the mouth.