JP3343060B2 - Field emission type cold cathode electronic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field-emission cold-cathode electronic device having a field-emission cold-cathode that emits electrons by a tunnel effect, and more particularly, to a display element in which a phosphor powder or the like is coated on the anode side. Field of the Invention The present invention relates to a field emission type cold cathode electronic device suitable for use as an electronic device.

[0002]

2. Description of the Related Art In recent years, attention has been paid to the high speed and controllability of electrons in a vacuum. FE: Field-Emission)
Development of cold cathodes (emitters) is underway.

In order to emit electrons with a field emission cold cathode, the wall of the energy difference of the work function is narrowed by an electric field,
It is necessary to transmit the potential wall through the tunnel effect. For that purpose, it is necessary that the surface of the emitter material is stable, the work function is low, and the electric field is high. Further, in order to obtain a high electric field by applying a voltage, a structure having a thin emitter tip is required. As one example, the Spindt method is known (CASpint; Journal of Applied Physics,
Vol. 47, 5248 (1976)).

In the Spindt method, as shown in FIG. 4A, a silicon dioxide (SiO ₂ ) film 2 or the like is formed as an insulating film on a silicon (Si) substrate 1 by CVD (Chemical Vapor Depth).
Then, a molybdenum (Mo) film 3 and an aluminum (Al) film 4 serving as gate electrodes are formed by, for example, a sputtering method. Next, as shown in FIG. 4B, the Al film 4, the Mo film 3 and the SiO ₂ film 2 are subjected to RIE.
(Reactive Ion Etching)
A pinhole 5 having a diameter of about 1.5 μm is formed.

Next, as shown in FIG. 4C, a metal serving as an emitter, for example, a Mo film 6 is vacuum-deposited. At this time, the Si substrate 1 is rotated, and Mo is vapor-deposited from the vertical direction. By utilizing the fact that the diameter of the pinhole 5 is closed together with the deposition of Mo, the tip of the tip which becomes the emitter 7 in the pinhole is sharp. A Mo film is deposited in a conical shape.

Next, as shown in FIG. 4D, the Al film 4 is removed by etching and the Mo film 6 deposited thereon is removed.
To form a field emission cold cathode having a cold cathode emitter (FE emitter) 7 composed of a Mo film gate 3 and a conical Mo film. In addition, as a method for producing an FE emitter, a transfer molding method as disclosed in Japanese Patent Application Laid-Open No. 6-36682 is known.

The above-mentioned field emission type cold cathode is finally disposed in a glass container (not shown) together with an anode (not shown) for capturing electrons, and the field emission type cold cathode is formed by performing vacuum sealing of the container. It becomes a cathode electronic device. As an application example of the field emission type cold cathode electronic device, the energy of electrons can be extracted as light by forming an anode with a transparent electrode and further applying and forming a phosphor powder. This enables use as a display element and attracts attention as contributing to the realization of a flat panel display.

However, the following problems have been encountered in display devices and the like to which this type of field emission cold cathode is applied. That is, since the phosphor applied to the anode side for display has low adhesion, a part of the phosphor powder is separated from the anode by electrostatic force or ion bombardment. Then, since the separated phosphor powder collides with the gate and the emitter, the flicker of the phosphor and the damage of the emitter may be caused. In particular, there is a problem that the electric field changes greatly in the switching operation, and the phosphor powder moves in response to the change, thereby increasing the damage to the emitter region.

[0009]

As described above, conventionally, in a field emission type cold cathode electronic device in which a phosphor powder or the like is coated on the anode side and used as a display element, one of the phosphor powders is applied by electrostatic force or ion bombardment. There is a problem that the portion peels off from the anode, which causes a flicker of the phosphor and a damage of the emitter.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent the occurrence of flickering of the phosphor and the occurrence of damage to the emitter.
An object of the present invention is to provide a field emission type cold cathode electronic device having a long life and high reliability.

[0011]

[Means for Solving the Problems]

(Configuration) In order to solve the above problem, the present invention employs the following configuration. That is, the present invention provides a field emission cold cathode including an emitter that emits electrons by a tunnel effect, a gate that electrically controls electrons emitted from the emitter, and an anode that captures electrons emitted from the emitter. The electronic device is characterized in that a fine particle adsorbing material film for adsorbing solid fine particles is formed in a part of the space containing the emitter, the gate, and the anode.

Here, preferred embodiments of the present invention include the following. (1) The fine particle adsorbing material film is made of Ga as a liquid metal or Ga
And alloys of group IIa as constituent elements. (2) The fine particle adsorbing material film is provided on the cold cathode substrate side on which the emitter and the gate are formed. (3) The fine particle adsorbing material film must be electrically floating or ground potential.

(Function) There are several methods for adsorbing fine particles (fine powder), but according to the inventors' intense research and experiments, no gas is generated when used in a high vacuum. It has been found that physical adsorption is desirable and that the surface tension of the liquid metal is suitable. In particular, the present inventors have found that Ga is extremely effective as a fine particle adsorbent, since it has a low vapor pressure, generates little gas, and has a high surface tension, so that projections are unlikely to occur and electron emission hardly occurs. . Also, when a small amount of group IIa element is mixed into Ga,
It was found that an effect of adsorbing residual gas was obtained in addition to the adsorption of fine particles.

According to the present invention, by providing the above-mentioned fine particle adsorbing material film in a part of the space accommodating the emitter, the gate and the anode, for example, a phosphor powder is applied to the anode to form a display element. In the configuration, even if the phosphor powder or the like is peeled off from the anode, it can be quickly adsorbed on the fine particle adsorbing material film . Therefore, it is possible to prevent the flicker of the phosphor and the occurrence of damage to the emitter due to the peeling of the phosphor powder and the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. (First Embodiment) FIG. 1 is a sectional view showing a schematic structure of a field emission type cold cathode electronic device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a vacuum vessel.
The field emission type cold cathode 20 and the anode part 30 are disposed opposite to each other. The field emission type cold cathode 20 is a Si substrate 2
1, SiO ₂ film 22, Si film (gate) 23, cold cathode emitter (FE emitter) 26, and fine particle adsorption electrode 2
8. That is, the SiO ₂ film 12 as an insulating film is formed on the Si substrate 11 and the SiO ₂ film 12
Are removed to expose the substrate surface. And
By depositing a Mo film in a conical shape on the exposed portion of the substrate, a cold cathode emitter (FE emitter) 26 is formed. Further, a Si film 23 serving as a gate electrode is formed on the SiO ₂ film 22, and a fine particle adsorption electrode 28 is formed in a region where a part of the Si film 23 is removed.

Here, the emitters 26 are arranged in a matrix to constitute a display element. The fine particle adsorption electrode 28 is formed by applying Ga which is a liquid metal, but an alloy of Ga and a group IIa element (for example, Be, Mg, Ca) may be used. Further, the fine particle adsorption electrode 28 may be provided adjacent to each individual emitter, may be provided for each group divided into a plurality of emitters, or may be provided only at one location. .

On the other hand, the anode portion 30 is
1, an anode 32, and a phosphor 33. That is, a transparent electrode (anode) 32 such as ITO is formed on the surface of the glass substrate 31, and the powder of the phosphor 33 is applied and formed on the surface of the anode 32.

Then, for example, the Si substrate 21 is grounded, a voltage of 0 V is applied to the emitter 26, and a voltage of 50 V is applied to the gate 23.
By applying a voltage of 1 kV to the anode 32, electrons emitted from the emitter 26 are controlled by the gate 23 and captured by the anode 32. At this time, electrons collide with the phosphor 33 to emit light, thereby functioning as a display element. Further, by independently controlling the electron emission from each emitter 26,
A two-dimensional image can be displayed.

In such a configuration, when a high voltage is applied between the emitter 26 and the anode 32 to emit electrons from the emitter 26, the electrons are emitted from the phosphor 33 on the anode side.
And the phosphor 33 emits light. At this time, since the adhesion of the phosphor 33 applied to the anode 32 is low, a part of the phosphor powder is peeled off by electrostatic force or ion bombardment. In the conventional device, the separated phosphor powder causes flickering and emitter destruction.

On the other hand, in the present embodiment, since the fine particle adsorption electrode 28 made of Ga is provided on a part of the SiO ₂ film 22 of the field emission type cold cathode 20, the phosphor powder separated from the anode 32 is fine particles. It is quickly adsorbed on the adsorption electrode 28 and does not drift in the vacuum vessel 10 for a long time. Therefore, it is possible to prevent the phosphor powder from colliding with the gate 23 and the emitter 26 and causing the flicker of the phosphor and the destruction of the emitter.

Since the phosphor powder separated from the anode 32 is generally positively charged, the fine particle adsorption electrode 28
Is desirably grounded (0 V) or floating. In addition, since it is not desirable that electrons are emitted from the fine particle adsorption electrode 28, the shape of the fine particle adsorption electrode 28 is desirably flat. From this point, Ga, which is a liquid metal, is extremely effective as the fine particle adsorption electrode 28.

Next, a method of manufacturing a field emission cold cathode according to the present embodiment will be described with reference to FIG. First, FIG.
As shown in FIG. 1A, a silicon dioxide (SiO ₂ ) film 22 is deposited on a Si substrate 21 as an insulating film to a thickness of about 1 μm by thermal oxidation or CVD, and then an S film serving as a gate electrode is formed.
The i film 23 and the Al film 24 are formed to a thickness of 300 and 100 nm, for example, by a sputtering method.

Then, as shown in FIG. 2B, the Al film 24, the Si film 23 and the SiO ₂ film 22 have a diameter of about 1 by selective etching of RIE using a first resist (not shown) as a mask. A pinhole 25 of about 0.5 μm is formed.

Next, as shown in FIG. 2C, a Mo film to be the emitter 26 is formed by vacuum sputtering. At this time, by rotating the Si substrate 21 and sputtering the emitter metal 27 from the vertical direction, the Mo film 26 is confined in the pinhole 25 by utilizing the fact that the diameter of the pinhole is closed with the deposition of the Mo film. Deposit in a shape.

Next, as shown in FIG. 2D, by removing the excess Mo film 26 deposited on the Al film 24 together with the etching removal of the Al film 24, the Si film 23 is used as a gate, and a cone is formed. The Mo film is used as a cold cathode emitter (FE emitter) 26. Thus, a field emission cold cathode is formed.

Next, as shown in FIG. 2E, unnecessary portions of the Si film 23 as a gate metal are selectively removed,
In this removed portion, a fine particle adsorption electrode 28 of Ga is formed to a thickness of 2 μm by vapor deposition or the like so as to be separated from the gate 23.

Then, the field emission cold cathode 20 having the structure shown in FIG. 2E is placed on an anode 32 made of a transparent electrode such as ITO formed on a transparent substrate 31 made of glass or the like.
The field emission type cold-cathode electronic device having the configuration shown in FIG. 1 was prepared by arranging in the vacuum vessel 10 together with the anode portion 30 provided with 3 and evacuating. Here, the phosphor 3
In forming 3, phosphor powder was dissolved in an organic binder or the like, applied to the anode 32 by printing or the like, and sintered at about 400 ° C. in an inert atmosphere and a vacuum atmosphere.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
FIG. 9 is a cross-sectional view for explaining the field-emission cold-cathode electronic device according to the embodiment, and particularly showing a manufacturing process of the field-emission cold-cathode.

First, as shown in FIG.
00) On the substrate 41, an SiO ₂ film is deposited as an anisotropic etching protection film 42 to a thickness of about 100 nm by a thermal oxidation method, and the SiO ₂ film 42 is selected with ammonium fluoride or the like using a resist (not shown) as a mask. The Si substrate 41 was anisotropically etched with potassium hydroxide aqueous solution using the remaining SiO ₂ film 42 as a mask to form a micron-sized V-shaped groove 43. Then, S
The iO ₂ film 42 is removed.

Next, as shown in FIG. 3B, thermal oxidation is performed again to form a 0.5 μm thick SiO ₂ film 44. Due to this thermal oxidation, the tip of the V-shaped anisotropic etching groove 43 becomes sharp. The SiO ₂ film 44 is also configured as an insulating film between the emitter and the gate.

Next, as shown in FIG. 3C, the Mo film 45 serving as an FE emitter is formed to a thickness of about 3 μm by sputtering or the like.
m and a thickness of 0.1 m for the adhesive layer 46.
It is formed to a thickness of 3 μm.

Then, as shown in FIG. 3D, a glass substrate 47 having a thickness of 0.5 mm is bonded to the bonding layer 46 by an electrostatic bonding method, and the Si (100) substrate 41 is bonded to an aqueous solution of potassium hydroxide or the like. It is removed by etching. By this etching, the V-shaped groove 43 is transferred in a pyramid shape.

Next, as shown in FIG. 3E, an Al film or a chromium (Cr) film serving as the gate 48 is formed to a thickness of 300 nm by, for example, a sputtering method. Here, the gate 48 may be a single layer of Al or Cr, or may be a laminated film.

Next, as shown in FIG. 3 (f), a resist 49 is applied to the entire surface, and the resist 49 is applied by CDE (Chem).
ical dry etching) until the tip 40 of the gate metal comes out.

Next, as shown in FIG. 3G, only the tip 40 of the gate metal is opened by etching using the remaining resist 49 as a mask, and the SiO ₂ film 44 is further formed.
By opening only the tip by etching, M
The end of the pyramid of the o-film 45 is exposed and becomes an FE emitter. Thereafter, the resist 49 is removed.

Next, as shown in FIG. 3H, the unnecessary portion of the gate 48 is removed except for the periphery of the emitter. Then, a fine particle adsorption electrode 50 containing Ga as a main component is formed in a removed portion of the gate 48 to a thickness of, for example, several μm by a vapor deposition method or a printing method so as to be separated from the gate 48.

Thereafter, in addition to the gate and the emitter, an anode coated with a phosphor and the like are arranged in a glass container as shown in FIG.
This is a field emission type cold cathode electronic device.

Also in this embodiment, the fine particle adsorption electrode 5
By providing 0, the phosphor powder or the like peeled off from the anode or the like can be quickly adsorbed, and flickering of the phosphor and destruction of the emitter can be suppressed.

The present invention is not limited to the above embodiments. In the embodiment, the display element has been described as an example. However, since the fine particle adsorbing material film adsorbs not only phosphor powder but also dust, an ultra-high-speed device using a field emission cold cathode, a power device other than the display element Etc. can be applied.

The fine particle adsorbing material film is not necessarily made of Ga.
The material is not limited to liquid metal such as, for example, any substance that does not generate gas and can adsorb fine particles on the surface. Further, the formation position of the fine particle adsorbing material film is not limited to the field emission type cold cathode side, but may be the anode electrode side, or may be any space in which the emitter, gate, anode and the like are accommodated. .

[0042]

As described above in detail, according to the present invention, fine particles such as phosphors having a low adhesion force are separated by electrostatic force or ion bombardment and collide with the emitter to cause flickering of the fluorescent light and destruction of the emitter. However, by providing the fine particle adsorption region, there is no flickering of the fluorescent light and no destruction of the emitter, and it is possible to improve the stability of the field emission type cold cathode and extend the service life.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a field emission type cold cathode electronic device according to a first embodiment.

FIG. 2 is a sectional view showing a manufacturing process of the field emission cold cathode used in the first embodiment.

FIG. 3 is a sectional view showing a manufacturing process of a field emission cold cathode used in the second embodiment.

FIG. 4 is a sectional view showing a manufacturing process of a conventional field emission cold cathode.

[Explanation of symbols]

10 ... vacuum vessel 20 ... field emission cathode 21, 41 ... Si substrate 22,42,44 ... SiO ₂ film 23 ... Si film (gate) 24 ... Al film 24 25 ... pinhole 26,45 ... Mo film (FE Emitter) 27 Mo film (emitter metal) 28 Fine particle adsorption electrode 30 Anode part 31 Transparent substrate 32 Anode 33 Phosphor 43 V-shaped groove 46 Ta adhesive layer 47 Glass substrate 48 Al film ( Gate) 49 ... Resist

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01J 29/94 H01J 31/12 H01J 1/30

Claims (1)

(57) [Claims] 1. A field emission cold cathode comprising: an emitter for emitting electrons by a tunnel effect; a gate for electrically controlling the electrons emitted from the emitter; and an anode for capturing the electrons emitted from the emitter. In the electronic device, a particulate adsorbing material for adsorbing solid particulates to a part of a space containing the emitter, the gate, and the anode
A field emission type cold cathode electronic device characterized by forming a film .