JP2000357452A - Manufacture for cold cathode element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve practicability even at low applied voltage by setting vapor depositing energy of an ion beam in a specific range and depositing it in an ion beam vapor depositing method. SOLUTION: During formation of an amorphous carbon film, a predetermined voltage is applied to each part to generate positive Cs ions from a Cs plasma ion source 8, negative ions are taken out with negative ion taking electrode 12 through a suppressor 9 to generate negative ion beams 17. These are converged through a lens 13. Next, an electron removing body 15 removes electrons contained in the negative ion beams 17, a deflection plate 16 flies only negative ions toward Al made negative plate 2, the amorphous carbon film is formed on the surface of the negative plate 2 in an ion beam vapor depositing method. Depositing energy E of the ion beam used here is set as 150 eV<=E<=1000 eV for suppressing electric insulation of the amorphous carbon film 3, expecting electric field effect to a film surface, forming an ion injection layer on the amorphous carbon film 3, and preventing disturbance of release of electric field from the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cold cathode device which emits electrons when an electric field is applied.

[0002]

2. Description of the Related Art Hot cathode devices and cold cathode devices are known as electron emitting devices. Hot cathode devices are used in fields typified by vacuum tubes, but have the problem that integration is difficult due to the application of heat. On the other hand, cold cathode devices are expected to be applied to flat panel displays, voltage amplifiers, high frequency amplifiers, and the like as devices that can be integrated because they do not use heat.

Conventionally, this kind of cold cathode device is manufactured by sputtering.

[0004]

However, the cold cathode device by sputtering has a problem that it does not emit electrons unless the applied voltage is relatively increased, that is, the field emission characteristics are low.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a manufacturing method capable of obtaining a highly practical cold cathode device capable of sufficiently emitting electrons even at a low applied voltage. .

According to the present invention, in order to achieve the above object,
In manufacturing a cold cathode device that emits electrons when an electric field is applied, the deposition energy E of the ion beam is set to 1
A manufacturing method for obtaining a cold cathode device made of an amorphous carbon film by applying an ion beam evaporation method set to 50 eV ≦ E ≦ 1000 eV is provided.

In the carbon ion beam deposition method, the deposition energy E affects the field emission characteristics of a cold cathode device made of an amorphous carbon film. Therefore, the deposition energy E
Is set as described above, an amorphous carbon film having excellent field emission characteristics, that is, a cold cathode device can be obtained.

In a carbon ion beam deposition method, when the deposition energy E of the ion beam is E ≒ 120 eV, the diamond property of the amorphous carbon film becomes the highest.
In this case, the electric insulation of the film is also high, and an electric field effect on the film surface cannot be expected, so that the emission electric field tends to increase. In consideration of this point, the lower limit of the deposition energy E is set to E = 150 eV. On the other hand, in a region where the deposition energy E exceeds 1100 eV, an ion implantation layer is formed on the amorphous carbon film, so that field emission from the film cannot be expected. Considering this point, the upper limit value of the deposition energy E is set to E = 1000 eV.

The amorphous carbon film is used alone,
For example, in order to improve the performance of a cold cathode device made of Si,
It is also used as a constituent material of the surface coating layer of the element.

[0010]

FIG. 1 shows a cathode unit 1 comprising a cathode plate 2 made of Al and a cold cathode element 3 formed on the surface thereof. The cold cathode device 3 is
When the ion beam deposition energy E is 150 eV ≦ E ≦ 10
It is composed of an amorphous carbon film formed by applying an ion beam evaporation method set to 00 eV.

In the carbon ion beam deposition method, the deposition energy E affects the field emission characteristics of the cold cathode device 3 made of an amorphous carbon film. Therefore, the deposition energy E
Is set as described above, an amorphous carbon film having excellent field emission characteristics, that is, the cold cathode device 3 can be obtained.

In the ion beam evaporation method, a positive ion beam or a negative ion beam is used. in this case,
The atomic density of the amorphous carbon film increases in the order of the positive ion beam evaporation method and the negative ion beam evaporation method, that is, the conductivity increases in this order, and the emission field decreases in this order. This difference in atomic density is due to the fact that the internal potential energy (electron affinity) of negative ions is lower than that of positive ions (ionization voltage).

Hereinafter, a specific example will be described.

[I] Formation of Amorphous Carbon Film by Negative Ion Beam Deposition Method FIG. 2 shows a known ultra-high vacuum type negative ion beam deposition apparatus (NIAB).
NIS: Neutral and Ionized Alkaline metal bombardment
type heavy Negative Ion Source). The apparatus comprises a Cs (cesium) plasma ion source 8 having a center anode pipe 5, a filament 6, a heat shield 7, and the like.
And a target electrode 11 having a target 10 made of high-purity high-density carbon, a negative ion extraction electrode 12, a lens 13, an electron remover 15 having a magnet 14, and a deflecting plate 16. ing.

In forming the amorphous carbon film 3 (for the sake of convenience, the same reference numerals as those of the cold cathode device are used), (a) a predetermined voltage is applied to each part as shown in FIG. ) Generating positive ions of Cs by the Cs plasma ion source 8;
(C) The target 10 is sputtered by positive ions of Cs to generate negative ions such as C. (d) The suppressor 9
Negative ions are extracted by the negative ion extraction electrode 12 through the negative electrode to generate a negative ion beam 17, (e) the lens 1
3, the negative ion beam 17 is converged by (3), the electrons contained in the negative ion beam 17 are removed by the electron remover 15, (g) only the negative ions are made to fly toward the cathode plate 2 by the deflection plate 16, Such a method was adopted.

FIG. 3 shows a mass spectrum of the negative ion beam 17. The main negative ions of the negative ion beam 17 are C ^- ions having 1 constituent atom and C ₂ ^- ions having 2 constituent atoms. However, the ion current is ^C -> ^C
₂ ^-.

Table 1 shows the conditions for forming the amorphous carbon film 3 in Examples 1 to 16 by the negative ion beam evaporation method. Example 1
16 had a thickness of 0.4 to 0.8 μm.

[0018]

[Table 1]

Next, about the center of Examples 1 to 16 was analyzed by Raman spectroscopy to determine whether or not they were amorphous. FIG. 4 shows the analysis result of Example 8, where the wave number 15
A broad Raman band centered around 00 cm ^-1 is observed. This proved that Example 8 was amorphous. The same results as in FIG. 4 were obtained for the other Examples 1 to 7, and 9 to 16.

In Examples 1 to 16, the emission electric field was measured by the method shown in FIG. That is, an Al conductive plate 19 is connected to a voltage-adjustable power supply 18, and the center of the conductive plate 19 is 0.8 cm long and 0.8 cm wide (0.64 cm ² ).
150 μm thick cover glass 21 having openings 20
And the amorphous carbon film 3 of the cathode unit 1 was placed on the cover glass 21, and an ammeter 22 was connected to the cathode plate 2. Next, a conductive plate 19 is
, A predetermined voltage was applied, and the current was read by the ammeter 22. Then, from the area of the measured current and the opening 20 determines the emission current density (μA / cm ^2), in consideration of practicality, when the emission current density reached 8 .mu.A / cm ^2, a voltage corresponding thereto The emission electric field (V / μm) was determined from the thickness of the cover glass 21.

Table 2 shows the deposition energy E for Examples 1-16.
And the emission field.

[0022]

[Table 2]

FIG. 6 is a graph showing the relationship between the deposition energy E and the emission electric field based on Table 2. As is apparent from FIG. 6, the deposition energy E is set to 150 eV ≦ E ≦ 10
When it is set to 00 eV, an amorphous carbon film 3 having a much lower emission electric field as in Examples 3 to 15 can be obtained. In the case of Examples 1 and 2, the emission electric field was high because the deposition energy E was E <150 eV, whereas in the case of Example 16, the emission electric field was high because the deposition energy E was E> 1000 eV. Has become.

This type of cold cathode device is applied to a flat panel display, a voltage amplifier, a high frequency amplifier, a high-precision close range radar, a magnetic sensor, a visual sensor, and the like.

[0025]

According to the present invention, by employing the above-mentioned means, it is possible to obtain a highly practical cold cathode device capable of sufficiently emitting electrons even at a low applied voltage. Can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cathode unit.

FIG. 2 is a schematic diagram of an ultra-high vacuum type negative ion beam evaporation apparatus.

FIG. 3 is a beam spectrum obtained by the apparatus.

FIG. 4 is a chart showing an analysis result of an amorphous carbon film by Raman spectroscopy.

FIG. 5 is an explanatory diagram of an emission field measurement method.

FIG. 6 is a graph showing the relationship between deposition energy E and emission electric field.

[Explanation of symbols]

 Reference Signs List 1 cathode unit 2 cathode plate 3 cold cathode device (amorphous carbon film)

Claims (2)

[Claims] When manufacturing a cold cathode device that emits electrons when an electric field is applied, an ion beam deposition method in which an ion beam deposition energy E is set to 150 eV ≦ E ≦ 1000 eV is applied. A method for producing a cold cathode device, comprising obtaining a cold cathode device comprising a crystalline carbon film. 2. The method according to claim 1, wherein the ion beam is a negative ion beam.