JPH09283063A - Field emission type display, manufacture thereof and manufacture of metal film for display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin uniform Al film on a fluorescent material layer of a field emission type display of small drive voltage. SOLUTION: Al20 and an anode substrate 2 are stored in the inside of a vacuum vessel. The inside of the vacuum vessel is placed in a high vacuum condition of 1×10<-5> Torr or more, He gas is introduced by a degree from several Torr to 1×10<-2> Torr. The Al20 is evaporated, the anode substrate 2 is heated to about 400 deg.C. An evaporated Al molecule Δ, repeating collision against an He molecule O with energy damped and a temperature difference from the anode substrate 2 decreased, leads thereto. The Al molecule grows as a flat large particle in a surface of a fluorescent material particle of a fluorescent material layer 6, an extremely thin fine holeless Al film 7 is uniformly formed in a surface of the fluorescent material layer 6. This anode substrate is used, a field emission type display is formed. Even by setting drive voltage of the field emission type display to several hundred to several kV higher than in the past, the fluorescent material layer 6 is coated with the Al film, so as to prevent worsening of a life characteristic of the fluorescent material layer 6, high emitting efficiency can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field emission display, a method of manufacturing the same, and a method of manufacturing an aluminum film useful for a display having a phosphor in a light emitting portion.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional field emission display 1
It is sectional drawing which shows the structure of 00. The field emission display 100 has an anode substrate 101 made of a translucent insulating material such as glass, and an insulative cathode substrate 102 facing the anode substrate 101 at a predetermined interval. There is a spacer member (not shown) between the outer peripheral portions of the substrates 101 and 102, and the space between the substrates 101 and 102 is maintained in a high vacuum state. On the inner surface of the anode substrate 101, an anode conductor 103 made of a transparent conductive film such as ITO (Indium Tin Oxide) is formed. A phosphor layer 104 is deposited on the surface of the anode conductor 103 to form an anode 105 which is a display section. The cathode substrate 10
On the inner surface of 2, the field emission cathode 106 (F
EC, Field Emission Cathode) has been formed. The field emission cathode 106 is insulated from the cathode conductor 107 formed on the inner surface of the cathode substrate 102, the resistance layer 108 formed on the surface of the cathode conductor 107, and the insulating layer 109 formed on the surface of the resistance layer 108. It has a gate 110 formed on the surface of the layer 109, and a cone-shaped emitter 111 formed on the resistance layer 108 inside the hole formed in the gate 110 and the insulating layer 109.

The conventional field emission display 1 described above
At 00, electrons are emitted from the emitter 111 due to the electric field formed by the gate 110, and the electrons strike the anode 105 to which a positive potential is applied, causing the phosphor layer 104 to emit light. Light emission of the phosphor layer 104 is observed from the outer surface side of the anode substrate 101 via the anode conductor 103 and the anode substrate 101.

In driving the field emission display 100 described above, the drive voltage applied to the anode conductor 103 is, for example, about 400 V, which is the drive voltage for the CRT or the like 10.
Significantly lower than ~ 30kV. In the conventional field emission display 100 driven at such a low voltage, electrons enter only near the surface of the phosphor layer 104 and emit light only near the surface of the phosphor. Therefore, in the conventional field emission display 100, a phosphor having high conductivity (that is, low resistance) is used, and the phosphor layer 104 is used.
It is difficult for the electrons to be charged.

[0005]

In the conventional field emission display 100, since the phosphor layer 104 is exposed as described above, if the driving voltage is increased to improve the emission brightness and the like, a high voltage is applied. Electrons are charged on the surface of the phosphor due to the injection of electrons accelerated by, and life characteristics are significantly reduced. CR of high voltage drive mentioned above
At T, the surface of the phosphor layer is covered with an aluminum film called a metal back, and electrons accelerated by a high voltage pass through the aluminum film and strike the phosphor layer to emit light. There is. The present inventor applies such an aluminum film to a field emission display in order to drive a field emission display with a higher drive voltage than before, without any problem, and by covering the phosphor layer with an aluminum film, The idea was to protect the phosphor layer from high-voltage accelerated electron bombardment. In order to develop this idea, the inventor diligently studied various methods of forming an aluminum film on the phosphor layer.

FIG. 5 is a diagram showing a method of forming an aluminum film on a phosphor layer which the present inventors have studied. In the method shown in FIG. 5, as shown in FIG.
The intermediate film 112 is formed on the surface of the phosphor layer 104 formed on the first side.
To flatten the surface of the phosphor layer 104,
An aluminum film 113 is vapor-deposited on it. FIG.
As shown in the enlarged view of FIG.
No. 3 is a stack of substantially spherical aluminum particles having a diameter of about 0.01 μm to 0.1 μm and a thickness of 0.2 μm.
It becomes 1 μm. With this thickness, electrons accelerated by a high driving voltage of the CRT can penetrate, but at most, electrons of a field emission display accelerated by a driving voltage of 10 kV or less pass through this to pass through the phosphor in the lower layer. It cannot emit light.

A method for transferring an aluminum vapor-deposited sheet to the surface of the phosphor layer formed on the anode side to form an aluminum film was also examined. However, even with this method, the structure and thickness of the aluminum film are shown in FIG. ) Method becomes almost the same.

In the method of FIG. 6, aluminum 121 is directly deposited on the surface of the phosphor layer 120 formed on the anode side without applying an intermediate film. Even with this method, the aluminum particles deposited are spherical with a small diameter, and a flat and uniform aluminum film cannot be formed. In particular, if it is made thin enough to be applied to a field emission display, it becomes porous and cannot serve as a coating.

Further, a method of directly depositing aluminum by a sputtering method without applying an intermediate film on the surface of the phosphor layer formed on the anode side was also studied, but the aluminum film obtained by this method also has a large diameter. It is made up of small spherical aluminum particles that become porous and cannot serve as a coating.

The present invention was made on the basis of the knowledge of the present inventor described above, and is a thin and uniform aluminum film or the like which can be applied to a field emission display having a driving voltage smaller than that of a CRT or the like. The purpose is to form a metal film on the phosphor layer.

[0011]

According to another aspect of the present invention, there is provided a field emission display in which a first substrate having a light transmitting property and an anode having a light transmitting property formed on an inner surface of the first substrate. A conductor, a phosphor layer formed on the surface of the anode conductor, a metal film formed on the surface of the phosphor layer, a second substrate facing the metal film, and an inner surface of the second substrate And a field emission type cathode formed on.

A field emission display according to a second aspect is the field emission display according to the first aspect, wherein the metal film is composed of a large number of flat metal particles deposited on the phosphor layer. It is characterized by that.

A field emission display according to a third aspect is the field emission display according to the first or second aspect, characterized in that the metal film is made of one metal selected from aluminum and copper. .

The field emission display according to claim 4 is the field emission display according to claim 1, 2 or 3, wherein the field emission cathode is provided between the metal film and the field emission cathode. It is characterized in that a control electrode for controlling the emitted electrons is provided.

According to a fifth aspect of the method for manufacturing a field emission display, a step of forming a transparent anode conductor on an inner surface of a transparent first substrate, and a step of forming the transparent anode conductor on the anode conductor. In the step of forming the phosphor layer and in the inert gas atmosphere in which the inert gas is introduced into the vacuum, the first
And heating the substrate to vaporize the deposited metal to form a metal film on the surface of the phosphor layer.

According to a sixth aspect of the present invention, there is provided a method for producing a metal film for a display, which comprises forming a metal film on a surface of a phosphor layer formed on a substrate having a light-transmitting property. In the inert gas atmosphere in which the inert gas is introduced into the vacuum, the substrate is heated and the vapor deposition metal is heated and evaporated to form a metal film on the surface of the phosphor layer.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A field emission display 1 (Field Emission Display) which is an example of an embodiment of the present invention.
) Will be described with reference to FIGS. As shown in FIG. 1, the field emission display 1 faces an anode substrate 2 (first substrate) made of a translucent insulating material such as glass and the anode substrate 2 at a predetermined interval. It has an insulating cathode substrate 3 (second substrate). There is a spacer member (not shown) between the outer peripheral portions of the substrates 2 and 3, and the space between the substrates 2 and 3 is maintained in a high vacuum state.

An anode 4 constituting a light emitting display surface is formed on the inner surface of the anode substrate 2. The anode 4 is divided into a predetermined pattern for each phosphor that emits red, green and blue colors. First, on the inner surface of the anode substrate 2, ITO (Indium
The anode conductor 5 made of a light-transmitting conductive film such as tin oxide) is formed. A phosphor layer 6 is deposited on the surface of the anode conductor 5, and an aluminum film 7 as a metal film is formed on the surface of the phosphor layer 6.

The aluminum film used as a metal back in a conventional CRT or the like is formed by laminating spherical aluminum particles having a small diameter to a thickness of 2000 angstrom to 1 μm. On the other hand, the aluminum film 7 in this example has a structure in which flatly deformed aluminum particles are densely adhered to the surface of the phosphor particles, as shown in FIG. 3 which is an explanatory view of the manufacturing method described later. Is. The thickness is several hundred angstroms, which is thinner than before, and 20
It is less than 00 angstroms (preferably about 400 angstroms to 500 angstroms).

As shown in FIGS. 1 and 2, a field emission cathode 8 (FEC, which is an electron source) is formed on the inner surface of the cathode substrate 3.
Field Emission Cathode) has been formed. The field emission cathode 8 is composed of a cathode conductor 9, an emitter 10 formed on the cathode conductor 9, a gate 11 formed above the emitter 10, and the like.

On the inner surface of the cathode substrate 3, a plurality of striped cathode wirings 12 are formed at a predetermined interval. In each cathode wiring 12, rectangular holes reaching the cathode substrate 3 are formed at predetermined intervals. A rectangular cathode conductor 9 is formed on the cathode substrate 3 in each hole of the cathode wiring 12 at a constant distance from the inner circumference of the hole of the cathode wiring 12. That is, the cathode conductor 9 is not directly connected to the cathode wiring 12, but is an island-shaped cathode conductor 9 arranged in the hole of the cathode wiring 12 apart from the cathode wiring 12. The cathode wiring 1
A resistance layer 13 is formed on the upper surfaces of 2 and the cathode conductor 9. The resistance layer 13 is also filled between the cathode conductor 9 and the cathode wiring 12. A gate 11 is formed on the cathode conductor 9 and the resistance layer 13 via an insulating layer 14. The gate 11 has a stripe shape orthogonal to the cathode wiring 12. A large number of holes are formed in the gate 11 and the insulating layer 14 above each cathode conductor 9. A cone-shaped emitter 10 is formed on the resistance layer 13 inside each hole.

When the cathode conductor 9 has an island shape as described above,
With respect to each of the multiple emitters 10 formed for each cathode conductor 9, the resistance value of the resistance layer 13 can be kept substantially constant while maintaining an appropriate value. The resistance value that each emitter 10 has with the cathode wiring 12 is between the resistance layer 13 between the emitter 10 and the cathode conductor 9 and the outer circumference of the cathode conductor 9 and the inner circumference of the hole of the cathode wiring 12. It depends on a certain resistance layer 13. In this example, the cathode conductor 9 is formed in an island shape in the hole of the cathode wiring 12, so that the emitters 10 on the cathode conductor 9 have the same resistance condition. Therefore, in each cathode conductor 9 which is a unit when driving the field emission cathode 8, the driving conditions of each emitter 10 are the same and the electron emission is uniform.

A protective electrode 15 as a control electrode for controlling the electrons emitted from the field emission cathode 8 is provided between the field emission cathode 8 and the anode 4. The protective electrode 15 prevents the emitter 10 from being damaged due to discharge from the anode 4 to the field emission cathode 8. The protective electrode 15 may be provided as necessary in consideration of the driving voltage and the like. Further, if necessary, a focusing electrode for focusing the electrons and causing them to strike the anode 4 may be provided as a control electrode.

The field emission display 1 is driven to display. The drive voltage applied to the anode 4 is a conventional field emission display 1 in order to improve the emission brightness of the anode 4.
1 to 10k higher than the drive voltage of CRT etc.
The range is about V, but in this example, it is set to 2 to 5 kV. By sequentially scanning the cathode wiring 12 and applying a selection signal to the gate 11 in synchronization with this, electrons can be emitted from the emitter 10 of an arbitrary cathode conductor 9.
The emitted electrons impinge on the opposing portions of the anode 4, easily penetrate the thin aluminum film 7, and cause the phosphor layer 6 to emit light with at least as high brightness as when not covered with the aluminum film 7. The light emission of the phosphor layer 6 is observed from the outer surface side of the anode substrate 2 via the anode conductor 5 and the anode substrate 2. In the field emission display 1 of this example, the driving voltage applied to the anode 4 is high, but the phosphor layer 6 is the aluminum film 7
Since it is covered with no gaps, it is less susceptible to damage, and its life does not deteriorate rapidly enough to pose a practical problem. Further, of course, the aluminum film 7 has high conductivity, so that the problem of charging by electrons does not occur even if the driving voltage is higher than that of the conventional field emission display as in this example.

Further, the field emission display 1 requires less energy for the electron source than a fluorescent display tube using a filament cathode as the electron source. In the case of a filament cathode, the electrons are emitted from a linear emission source, and therefore the distance between the cathode and the anode must be set to some extent in order to diffuse the electrons.
Is a planar emission source, the distance between it and the anode 4 can be reduced, and a thin display element is obtained.

Next, the manufacturing process of the field emission display 1 will be described. First, the process of forming the field emission cathode 8 on the cathode substrate 3 will be described. (1) The cathode substrate 3 is washed to remove organic substances on the surface. As a cleaning method, there are a wet method using water and a dry method using ozone. In the case of the dry type, it is possible to use a cleaning device that sprays ozone while cleaning the cathode substrate 3 by a belt type transfer mechanism.

(2) On the inner surface of the cathode substrate 3, Nb is deposited on the entire surface by sputtering to a thickness of 0.4 μm. This Nb film is patterned by a photolithography technique. As a result, the stripe-shaped cathode wiring 12 and the island-shaped cathode conductor 9 described above are formed.

(3) A film of amorphous silicon having a thickness of 0.8 μm is formed on the cathode conductor 9 and the cathode wiring 12 by the CVD method and is patterned by the photolithography method to form the resistance layer 13. . If the surface of the resistance layer 13 is roughened by the etching used in the photolithography method and it becomes difficult for the emitter 10 formed in a later step to adhere to the resistance layer 13, the emitter 10 may be formed as necessary.
The Cr layer may be formed only on the portion of the resistance layer 13 that forms.

(4) SiO ₂ is formed on the entire surface by plasma CVD to a thickness of 1 μm to form the insulating layer 14. Then, Nb is formed to a thickness of 0.4 μm by the sputtering method and patterned by the RIE method to form the gate 11.

(5) A hole having a diameter of about 1 μm is formed in the gate 11 and the insulating layer 14 by the photolithography method and the RIE method. About 100 to several thousands are formed for each cathode conductor 9. An aluminum peeling film is formed on the surface of the gate 11. EB
Mo is obliquely vapor-deposited from the peeling film side by the vapor deposition method to form the cone-shaped emitter 10 on the resistance layer 13 inside the holes. The peeling film is peeled off from the gate 11 to remove the peeling film and Mo deposited on the peeling film.

Next, the process of forming the anode 4 on the anode substrate 2 will be described. (1) The anode substrate 2 is washed. The cleaning method is the same as that for the cathode substrate 3. (2) An ITO film having a thickness of 0.15 μm is formed on the inner surface of the anode substrate 4 by a sputtering method, and patterned by a photolithography method to form an anode conductor 5. The phosphor layer 6 is formed on the anode conductor 5 by the slurry method. That is, a phosphor layer forming liquid containing a phosphor is placed on the anode substrate 2, the anode substrate 2 is rotated at an appropriate rotation speed to spread the phosphor layer forming liquid on the anode substrate 2 by centrifugal force, and patterning is performed. Then, the phosphor layer 6 is formed.

(3) An aluminum film 7 is formed on the phosphor layer 6 by a vapor deposition method. In this step, a vacuum container equipped with a heating means for the vapor deposition substance, a heating means for the vapor-deposited body, and a vacuum device is used. As shown in FIG. 3, aluminum 20 as a vapor deposition material and the anode substrate 2 as an object to be vapor-deposited are housed in a vacuum container and placed at predetermined positions. The inside of the vacuum vessel is set to a high vacuum state of 1 × 10 ⁻⁵ Torr or more. In this, an inert gas such as He is added from several Torr to 1
About 10 ^-2 Torr is introduced to make an inert gas atmosphere.

In the vacuum container, the aluminum 20 is heated by a heating means such as an electron beam or resistance heating until it exceeds the melting point, and evaporated. At this time, the anode substrate 2 in the vacuum container is also heated. The heating temperature of the anode substrate 2 is preferably close to the melting point of the vapor deposition material, and is a temperature at which the anode substrate 2 is not damaged by heat. In this example, the melting point of aluminum is 6
The temperature was changed from 360 ° C, which is 300 ° C lower than 60 ° C, to 400 ° C.

As shown in FIG. 3, aluminum molecules evaporated from aluminum (indicated by Δ in the figure) repeatedly collide with He molecules (indicated by ○ in the figure), energy is attenuated, and reaches the anode substrate 2. At times, the temperature difference between the anode substrate 2 heated to about 400 ° C. is small. Therefore, the aluminum molecules grow as flat large particles on the surface of the phosphor particles of the phosphor layer 6 as shown in the drawing, and an extremely thin and dense aluminum film 7 having no pores is uniformly formed on the surface of the phosphor layer 6. To be done.

The degree of flatness of the aluminum particles is, for example, about 10 to 30 in the long direction with respect to the thickness 1. Therefore, the aluminum film 7 is composed of a single layer of particles having a thickness of 400 to 500 angstroms (0.
If it is about 04 to 0.05 μm), the radius of the aluminum particles is about 4000 to 15000 angstroms (0.4 to 1.5 μm).

In the method of manufacturing the field emission display 1 described above, the inside of the vacuum chamber is set to the He atmosphere in order to form the aluminum film 7, but another inert gas (Ne,
Ar, Kr, Xe, Rn) may be used. Further, although the aluminum film 7 is formed as the metal film, if the metal does not react with the phosphor and has a relatively low melting point, the metal film having the same structure as the aluminum film 7 can be produced by the manufacturing method. . For example, copper can be used.

Although the field emission type display 1 has been described in the above-mentioned example, the technique of forming a thin and dense metal film made of flat and large metal particles on the phosphor layer has a phosphor layer in the display portion. Can also be applied to flat display devices such as flat CRTs, high voltage VFDs, and light emitting devices for large-sized display devices.

[0038]

According to the present invention, since a dense metal film made of flat metal particles can be formed on the phosphor layer, the driving voltage of the field emission display is higher than the conventional one by several hundreds to several kV. Even in this case, high luminous efficiency can be realized without impairing the life characteristics of the phosphor layer.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a plan view showing a first example of an embodiment of the present invention.

FIG. 3 is a diagram schematically showing a step of forming an aluminum film 7 in the first example of the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a conventional field emission display.

FIG. 5 is a diagram for explaining a conventional method of manufacturing an aluminum film.

FIG. 6 is a diagram for explaining a conventional method of manufacturing an aluminum film.

[Explanation of symbols]

 1 Field Emission Display 2 Anode Substrate as First Substrate 3 Cathode Substrate as Second Substrate 5 Anode Conductor 6 Phosphor Layer 7 Aluminum Film as Metal Film 8 Field Emission Cathode 15 Protective Electrode as Control Electrode

Claims (6)

[Claims] 1. A first substrate having a light-transmitting property, and the first substrate.
A transparent anode conductor formed on the inner surface of the substrate of
A phosphor layer formed on the surface of the anode conductor, a metal film formed on the surface of the phosphor layer, a second substrate facing the metal film, and an inner surface of the second substrate. Field emission display having an improved field emission cathode. 2. The field emission display according to claim 1, wherein the metal film is composed of a large number of flat metal particles adhered to the phosphor layer. 3. The field emission display according to claim 1, wherein the metal film is made of one metal selected from aluminum and copper. 4. The field emission display according to claim 1, wherein a control electrode for controlling electrons emitted from the field emission cathode is provided between the metal film and the field emission cathode. . 5. A step of forming a transparent anode conductor on the inner surface of a transparent first substrate, a step of forming a phosphor layer on the anode conductor, and an inert gas in a vacuum. A step of heating the first substrate and heating and evaporating the deposited metal in an inert gas atmosphere into which a gas has been introduced to form a metal film on the surface of the phosphor layer. Production method. 6. A method of manufacturing a metal film for a display, which comprises forming a metal film on the surface of a phosphor layer formed on a light-transmitting substrate, wherein an inert gas atmosphere in which an inert gas is introduced A method for producing a metal film for display, wherein the metal film is formed on the surface of the phosphor layer by heating the substrate and heating and evaporating the deposited metal.