JPH07114106B2 - Method for manufacturing electron-emitting device - Google Patents

Description

The present invention relates to a method for manufacturing an electron-emitting device.

[Prior Art] Conventionally, as an element that can emit electrons with a simple structure,
For example, a cold cathode device announced by MI Elinson is known. [Radio Engineering Electron Physics (Ra
dio Eng. Electron. Phys.) Volume 10, pp. 1290-1296, 1965
This makes use of the phenomenon in which electron emission occurs when a current flows through a small-area thin film formed on a substrate in parallel to the film surface, and is generally called a surface conduction electron-emitting device. There is.

As the surface conduction electron-emitting device, one using a SnO ₂ (Sb) thin film developed by Elinson et al., One using an Au thin film [G.Dittmer: “Thin Solid Films "), Volume 9, 317
Page, (1972), by ITO thin film [M. Hartwell and CGFonstad: “IEEE Trans.ED C”
onf. ") 519, (1975)], by carbon thin film [Hiraki Araki et al.," Vacuum ", Vol. 26, No. 1, p. 22, (1983).
Years)] etc. have been reported.

The typical device configuration of these surface conduction electron-emitting devices is described in Section 5.
Shown in the figure. In the figure, 13 and 14 are electrodes for obtaining electrical connection, 15 is a thin film formed of an electron emitting material, 16 is a substrate, and 17 is an electron emitting portion.

Conventionally, in these surface conduction electron-emitting devices, an electron-emitting portion is formed in advance by an energization process called forming before electron emission. That is, by applying a voltage between the electrode 13 and the electrode 14, to energize the thin film 15,
The Joule heat generated thereby locally destroys, deforms or modifies the thin film 15 to form an electron emitting portion 17 in an electrically high resistance state, thereby obtaining an electron emitting function.

[Problems to be Solved by the Invention] However, the conventional forming by the above-described energization treatment has the following problems.

During energization, the thin film may peel due to the difference in thermal expansion coefficient between the substrate and the thin film. Therefore, there is a limit on the upper limit of the heating temperature and the combination of selection of the substrate material and the thin film material.

Since the substrate is also locally heated during energization, a fatal crack may occur.

The degree of change in the film due to energization, for example, the degree of local breakage, deformation or alteration, tends to vary among a plurality of elements formed in the same substrate, and the place where the change occurs tends to be inconsistent.

For this reason, when the device is made to function as an electron-emitting device, the amount of current and efficiency, the electron emission location, the shape of the emitted electron beam, and the like vary from device to device.

A relatively large amount of electric power is required until the forming is completed. Therefore, when a large number of elements are formed on the same substrate and forming is performed simultaneously, a large capacity power supply is required.

The conventional forming process from energization to cooling requires a relatively long time. Therefore, it takes a lot of time to form many elements.

Due to the above-mentioned problems, the surface conduction electron-emitting device has not been positively applied industrially even though it has an advantage that the device structure is simple.

The present invention has been made in order to eliminate the drawbacks of the conventional example as described above, and the quality equal to or higher than that of the electron-emitting device obtained by the forming process without performing the process called the conventional forming as described above. It is an object of the present invention to provide an electron-emitting device having a novel structure having the above-mentioned characteristics and less variation in characteristics.

[Means for Solving the Problem] It is considered that the mechanism of electron emission from the electron-emitting device according to the present invention is substantially similar to that of the conventional electron-emitting device by forming. That is, in the conventional element formed by forming, a part of the film has a high resistance due to forming, and a narrow crack of 1 μm or less is formed in this part, and a film having a small island structure is formed between the cracks. There is. In the element formed by forming, the shape, width, and shape and size of the cracks change intricately even if the forming conditions are made constant, and it is extremely difficult to make them constant.

The present invention firstly provides a means for easily manufacturing by controlling the shape and width of the crack to be constant without resorting to forming means, and to provide an electron-emitting device having uniform characteristics. Is.

Secondly, it provides a means for making the structure and size of the island-like structure in the crack constant, and thereby provides an electron-emitting device having uniform characteristics.

That is, according to the present invention, a step of forming a step forming layer made of an insulator in which conductive fine particles are dispersed is formed on a part of a substrate, and a first step facing at least a part of a side surface of the step forming layer. And a step of forming an electrode and a second electrode on the substrate and the step forming layer, respectively.

Furthermore, the present invention provides a step of forming a first electrode on a substrate, a step of laminating an insulating layer in which conductive fine particles are dispersed on the first electrode, and a step of forming an insulating layer on the insulating layer. A step of laminating a layer of an electrode material, and patterning the layer of the insulator and the layer of the electrode material respectively to form a step forming layer made of the insulator, and the electrode material on the step forming layer. And a step of forming a second electrode facing the first electrode on at least a part of a side surface of the step forming layer, the manufacturing method of the electron-emitting device.

In the electron-emitting device of the present invention, the gap between the first electrode and the second electrode facing each other on the side surface of the step forming layer corresponds to a crack in the device formed by the conventional example, and the fine particles correspond to islands. Becomes Also, the position of these electrode intervals,
It is possible to control the shape, size, particle size of fine particles, and structure such as dispersion state, and it is also possible to significantly widen the selection range of materials.

The present invention will be described in detail below.

1 (a), (b), (c) and FIG. 2 are a manufacturing process sectional view and an element plan view showing an example of the present invention. In the figure, 1 and 2 are electrodes for obtaining electrical connection, and 3
Is a substrate, 4 is fine particles, 5 is a step forming layer containing fine particles 4 dispersed therein, 6 is a step portion of the step forming layer, and 7 is an electrode interval.

In FIG. 1 (c), in the electron-emitting device of the present invention, the first electrode 1 and the second electrode 2 have electrode gaps in the side surface of the step forming layer 5 in which the conductive fine particles 4 are dispersed, that is, in the step portion 6. 7
Electrons are emitted from the fine particles 4 by applying a voltage between the electrodes 1 and 2.

Next, an example of the manufacturing method of the present invention will be described with reference to FIGS. 1 (a), (b), (c) and FIG.

First, the step forming layer 5 containing fine particles is deposited on the substrate 3 made of glass or ceramics by a liquid coating method or the like (see FIG. 1A).

Next, the step forming layer 5 is formed by the photolithography etching method so as to obtain the step 6 in the substantially central portion of the substrate 3 (first step).
See FIG. (B)).

Further, electrodes 1 and 2 are deposited on the step forming layer 5 and the substrate 3 so that at least a part of the side wall of the step 6 is not exposed, and an electrode interval 7 is formed (see FIG. 1 (c)). .

The electron-emitting device of the present invention can be obtained by the above steps. This device is placed in a vacuum container, a voltage is applied to electrodes 1 and 2, and an extraction electrode plate (not shown) is arranged facing the upper surface of the device to apply a high voltage, so that electrons are emitted from near the electrode interval 7. Is released.

According to the above steps, the crack in the forming element of the conventional example corresponds to the electrode interval 7. The electrode interval 7 in the present invention is controlled by the height of the step portion 6, that is, the film thickness of the electrode 1 deposited on the substrate 3 with respect to the film thickness of the step forming layer 5. Generally, film thickness control by deposition is relatively easy and highly accurate. Especially in the vacuum deposition method, it is easy to control the deposited film thickness up to several 10Å.

Therefore, as for the electrode interval 7, it is possible to obtain an interval size of about several tens of Å by controlling the deposited film thickness of the electrode 1 with high accuracy and to make the interval size highly accurate. The position and shape of the electrode gap portion can be controlled by the position and shape of the step portion 6 obtained by the photolithographic etching method.

The island structure in the forming element of the conventional example corresponds to the structure of the fine particles 4, and fine particle powder, an organometallic compound, or the like is mixed and dispersed in a material that forms the step forming layer 5, such as a liquid coating agent that forms an insulating film. It is obtained by coating the substrate 3 by spin coating, dip coating, or the like and baking.

Therefore, the particle size, dispersion state, etc. of the fine particles 4 can be controlled by the particle size of the fine particles, the type of the organometallic compound, the firing conditions, the mixing ratio with the liquid coating agent, the dispersion conditions, and the like.

In the present invention shown in the above examples, as the material of the electrode,
Widely used as surface conduction electron-emitting devices conventionally, for example, SnO ₂ , In ₂ O ₃ , metal oxides such as PbO,
Metals such as Au and Ag, carbon, and various semiconductors that are suitable as the electron-emitting material can be used by themselves. However, in the present invention, since the fine particles relating to electron emission are separately arranged, a material suitable for the electrode can be used as the electrode material other than the above. For example, withstand voltage,
Heat resistance, workability, oxidation resistance, life, amount of current that can be taken out,
The electrode material can be selected and used in consideration of the specific resistance and the like. For example, Cu, Al, Ni, Pd, Pt, W, Ta, Mo, Cr, Ti and the like, but not limited thereto.

The film thickness of the electrode is preferably a thickness used for a normal surface conduction electron-emitting device, and it is usually 0.01 to 5 μm, preferably 0.01 to 2 μm, although it depends on the type of material used.

Further, as the fine particle material involved in electron emission, for example, a substance that easily emits an electric field from an electron, a substance that easily emits a secondary electron, or a substance that easily emits an electron by the impact of an electron and has high heat resistance and corrosion resistance If it is good, for example,
W, Ti, Au, Ag, Cu, Cr, Al, P with low work function and high heat resistance
Metals such as t and Pd, oxides such as SnO ₂ and In ₂ O ₃ , carbon, or a mixture of the above, but not limited thereto.
The size of the fine particles is usually preferably several tens to several thousand Å in diameter. This size is a size easily obtained by the above method.

An insulating material is used as the material of the step forming layer.
For example _{SiO 2, Si 3 N 4,} MgO, TiO 2, Ta 2 O 5, Al 2 O 3 or the like or a laminated material or may be a mixture, this does not apply as the material.

The film thickness of the step forming layer differs depending on the film thickness of the deposited electrode. However, if it is considered that the size of the electrode spacing is simply a value obtained by subtracting the deposited electrode film thickness from the step formation layer, the step formation layer is calculated from the desired electrode spacing dimension value and the deposited electrode film thickness value.

The size of the electrode interval may be several tens of μm to several μm.
In particular, the smaller the gap between the electrodes, the higher the electron emission efficiency (the ratio of the amount of emitted electrons to the current flowing between the electrodes).
Tended to improve. Further, in the element according to the present invention, the fine particles are fixed by the step forming material. Therefore, even in the electron emission state due to the high electric field from the electrode, the structure is such that the movement and deformation do not easily occur, and stable electron emission can be obtained.

As can be easily understood from the above description, in the electron-emitting device according to the present invention, first, what corresponds to the narrow crack of the conventional example is the electrode interval 7 in the step portion 6, which is controlled by the electrode film thickness. Therefore, this electrode interval 7 is from several tens of Å to several μm
It can be easily controlled to a certain degree and formed uniformly. Further, the position and shape of the electrode interval 7 portion can be controlled by the position and shape of the step portion 6 obtained by photolithography or the like. further,
Since the fine particles 4 correspond to the island-like structure and are made of fine particles or an organometallic compound, the size and dispersion state can be easily controlled and a uniform structure can be formed.

Incidentally, there is no established theory about the mechanism of electron emission from the electron-emitting device according to the present invention, but it is considered that it is almost as follows.

That is, field emission due to application of a voltage between narrow insulating layers, electrons from electrodes, etc. are secondary electron emission due to diffraction, scattering, or collision by the island-shaped fine particles or counter electrodes, thermal electrons, Electron emission by hopping electrons, Auger electrons, etc. can be considered.

In the electron-emitting device described above, the electrode interval 7 corresponding to the narrow crack in the conventional example is controlled by the electrode film thickness.
With the structure shown in FIG. 6C, the electrode spacing 11 can be controlled by the film thickness of the step forming layer 9.

In this method, first, the electrode 8 is deposited and formed on the substrate 3 (see FIG. 3 (a)), and then the step forming layer 9 containing the fine particles 4 and the electrode material 12 are deposited (see FIG. 3 (b)). )), The electrode 10 and the electrode gap 11 are formed by the photolithographic etching method to form an electron-emitting device (see FIG. 3 (c)). According to this method, the electrode interval 11 can be controlled by the film thickness of the step forming layer 9. The step forming layer 9 is generally obtained by a liquid coating method or the like, but can be uniformly manufactured by controlling from several hundred Å to several μ depending on the coating method and the preparation of the coating agent. Further, each material and size in this method may be the same as those described above.

[Example] Example 1 An electron-emitting device having the embodiment shown in Fig. 2 was obtained based on the manufacturing steps shown in Figs. 1 (a) to 1 (c).

That is, a SiO ₂ liquid coating agent (OCD manufactured by Tokyo Ohka Kogyo Co., Ltd.) is mixed with an organic solvent containing an organopalladium compound (Catapaste CCP manufactured by Okuno Chemical Industries Co., Ltd.) on a clean quartz glass substrate having a thickness of about 1 mm, and SiO ₂ : Pd is added. A solution having a molar ratio of about 10: 1 was prepared and spin-coated with a spinner. Then about
By firing at 400 ° C. for 1 hour, a SiO ₂ step forming layer 5 containing Pd particles 4 having a film thickness of about 1500 Å was obtained (see FIG. 1 (a)).

Next, the step forming layer 5 is etched with a hydrofluoric acid aqueous solution by a photolithography etching method, and the height of about 1500
The step portion 6 of Å was formed (see FIG. 1 (b)).

After that, make sure that the step 6 is not completely covered and the film thickness is about 50.
0Å Ni electrodes 1 and 2 were deposited and formed in the shape shown in FIG. 2 by mask EB vapor deposition. In FIG. 2, the size is l = 2 mm and W = 0.3 mm. At this time, the electrodes 1 and 2 have a certain interval and are opposed to each other via the side wall of the step portion 6 of the step forming layer 5 containing the fine particles 4. This space is referred to as an electrode space 7 (see FIG. 1 (c)).

As a result of measuring the electron emission characteristics of the electron-emitting device obtained in the above process, the emission current I _e = 2.5 μA and the output efficiency α = 5 × 10 5.
An electron emission of about ^-3 was obtained.

Example 2 An electron-emitting device having a structure in which a step forming layer was sandwiched between electrodes as shown in FIG. 4 was produced based on the manufacturing steps of FIGS. 3 (a) to 3 (c) described above.

That is, the film thickness is about 500 on a clean quartz glass substrate with a thickness of about 1 mm.
A Ni electrode of Å was deposited by the EB vapor deposition method and formed into a shape shown in FIG. 4 by the photo-sori etching method to form the electrode 8 (see FIG. 3 (a)).

Next, an SiO ₂ step forming layer 9 containing Pd particles 4 was deposited on the surface of the electrode 8 and the substrate 3 by the same method as in Example 1 by EB vapor deposition so as to have a film thickness of about 1000 Å. Further, a Ni thin film having a film thickness of about 1000 Å was deposited on the SiO ₂ step forming layer 9 by EB vapor deposition to form an electrode material 12 (see FIG. 3 (b)).

Then, as shown in FIG. 4, a photoresist having a shape of an electrode 10 slightly overlapping with the electrode 8 at the center of the substrate was formed on the Ni thin film. The electrode material 12 and the step forming layer 9 are etched in the shape of this photoresist, and then the resist is peeled off to form an electrode.
10 and electrode spacing 11 were formed. The size other than the film thickness of each material was the same as in Example 1.

As a result of measuring the electron emission characteristics of the electron-emitting device obtained in the above steps, the same electron emission as in Example 1 was obtained.

Further, in the second embodiment, the step forming layer 9 has the same shape because it is etched by the same photoresist as the electrode 10, but the electrode 10 and the step forming layer 9 can be formed by etching with a photoresist having another shape. is there. However, in this case, when the electrode interval of 11 parts is formed, the second embodiment is also used.
Similarly, it is preferable to etch the electrode material 12 and the step forming layer 9 in the same shape with the same resist. This is because no uneven portion is formed on the side wall portions of the step forming layer 9 and the electrode 10 at the electrode interval 11 by the resist patterning deviation.

As described above, in Examples 1 and 2, the organic solvent of the organometallic compound was used as the fine particle material, but a similar electron-emitting device can be obtained even with a SiO ₂ liquid coating agent in which SnO ₂ fine particles having a primary particle size of about 100Å are dispersed. I was able to.

EFFECTS OF THE INVENTION As described above, according to the present invention, the first electrode 1 and the second electrode 1 facing each other with an electrode interval on the side surface (that is, the step portion) of the step forming layer in which the conductive fine particles are dispersed and arranged. Since this is an electron-emitting device that emits electrons by arranging the electrodes and applying a voltage between the electrodes, the electron-emitting device can be provided without performing the forming treatment as in the conventional example.

Therefore, the electron-emitting device according to the present invention has no conventional disadvantages associated with the forming process, and can easily manufacture a large number of devices with little variation in characteristics, which is extremely useful in industry. Further, since the electrode spacing can be controlled by the electrode film thickness or the film thickness of the step forming material, the size of several hundred Å to several μm can be easily controlled, so that the degree of freedom in designing the electron-emitting device is greatly expanded. . Further, since the fine particles related to electron emission and the electrode for applying a voltage to the fine particles are separately configured, it is possible to select an appropriate material for each and it is extremely useful in improving the performance of the electron-emitting device.

[Brief description of drawings]

1 is an explanatory view of a manufacturing process showing a first embodiment of the present invention, FIG. 2 is a plan view showing a first embodiment, and FIG. 3 is a manufacturing process showing a second embodiment of the present invention. 4 is a plan view showing a second embodiment, and FIG. 5 is a plan view of a conventional electron-emitting device.

Claims (2)

[Claims] 1. A step of forming a step forming layer made of an insulating material in which conductive fine particles are dispersed on a part of a substrate, and first electrodes facing each other on at least a part of side surfaces of the step forming layer. And a step of forming a second electrode on the substrate and on the step forming layer, respectively. 2. A step of forming a first electrode on a substrate, a step of laminating an insulating layer in which conductive fine particles are dispersed on the first electrode, and a step of laminating on the insulating layer. A step of laminating a layer of an electrode material, patterning the layer of the insulator and the layer of the electrode material respectively to form a step forming layer made of the insulator, and forming the step forming layer from the electrode material on the step forming layer. And a step of forming a second electrode facing the first electrode on at least a part of a side surface of the step forming layer.