JPH1050206A - Manufacture of field emission element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a field emission element by which stable field emission is conducted even at a low degree of vacuum. SOLUTION: An cathode substrate 1 in which emitters 8 are formed and a substrate made of emitter material or an anode substrate 10 made of the emitter material formed of a thin film or a thick film are oppositely arranged in a vacuum vessel 0, and drive voltages (VBE, VA) are applied across the cathode substrate 1 and the anode substrate 10 so that electron beams emitted from the cathode substrate 1 are hit to the anode substrate 10 and the emitter material is electric field-deposited on the emitters 8 so as to manufacture field emission elements. The emitters 8-formed cathode substrate 1 and an anode substrate are confronting arranged in the vacuum vessel 0, and in a state where the drive voltages (VBE, VA) are applied across the cathode substrate 1 and the anode substrate, hydrocarbon gas is introduced so that the electron beams emitted from the cathode substrate 1 are hit to the anode substrate and the ions of the hydrocarbon gas are adsorbed on the emitters 8 so as to manufacture the field emission elements.

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 field emission device.

[0002]

2. Description of the Related Art An electric field applied to a metal or semiconductor surface is 10
^At about ⁹ [V / m], electrons pass through the barrier due to the tunnel effect, and electrons are emitted in a vacuum even at room temperature. This is called field emission, and a cathode that emits electrons based on this principle is called a field emission cathode (hereinafter referred to as FEC).
It is called).

In recent years, it has become possible to manufacture a surface emission type field emission cathode composed of a micron size field emission cathode by making full use of semiconductor processing technology. A large number of field emission cathodes are formed on a substrate. The device is expected to be an element constituting a flat display device or various electronic devices by irradiating electrons emitted from the respective emitters to a phosphor screen formed on an anode substrate.

FIG. 9 is a diagram showing a configuration example of a cathode substrate and an anode substrate. The cathode substrate 100 is composed of a cathode 102 made of a metal layer, a resistance layer 103 made of amorphous silicon or the like, an insulating layer (SiO2 layer) 104 formed by thermally oxidizing silicon on a substrate 101 made of glass or the like,
Then, a gate 105 made of a metal layer of niobium or the like is sequentially formed by vapor deposition or the like. Further, after a photoresist (not shown) is applied on the gate 105, patterning and etching are performed, and an opening 106 is formed in the gate 105 and the insulating layer 104 as illustrated.

Next, the photoresist is removed and the substrate 10 is removed.
While rotating 1, a release layer (not shown) is deposited by rotating evaporation of aluminum from an oblique direction to the substrate surface. Then, the release layer is selectively deposited only on the surface of the gate 105 without being deposited in the opening 106. Further, when, for example, molybdenum is deposited from above the release layer, the deposited layer is placed on the release layer in the opening 106 opened by etching.
07 accumulate in the form of a cone. Thereafter, the gate 105
Removal of the overlying release and deposition layers by etching yields an FEC with the structure shown.

When the FEC shown in FIG. 1 is manufactured by using the semiconductor integration technology, the distance between the cone-shaped emitter 107 and the gate 105 can be made submicron. By applying a voltage of volt, electrons can be emitted from the emitter 107. When a large number of FECs are integrated on the substrate 101, the pitch between the emitters 107 can be made to be 5 to 10 microns.
It can be provided on a single cathode substrate 100.

On the anode substrate 110, a transparent conductive film 112 made of, for example, ITO is formed on a substrate 111 made of, for example, glass, and a phosphor 113 made of, for example, ZnO, which emits green light. It has been applied. Then, the cathode substrate 100 and the anode substrate 110
Is vacuum sealed while maintaining a gap of, for example, about 200 μm.

As described above, a surface emission type FEC can be manufactured, and it has been proposed that this FEC element be applied to a fluorescent display device, a CRT, an electron microscope, and an electron beam device.

FIG. 10 is a perspective view of such a surface emission type FEC element. In this figure, a cathode 102 is formed on a substrate 101, and a resistance layer 103 is formed on the cathode 102. A cone-shaped emitter 107 is formed on the resistance layer 103. Further, a gate 105 is provided on the cathode 102 via an insulating layer 104, and a cone-shaped emitter 107 is formed through a round opening 106 provided in the gate 105.
The tip of is facing.

In the surface emission type FEC thus formed, when a driving voltage VGE of several tens of volts is applied between the gate 105 and the cathode 102, electrons are emitted from the emitter 107 and emitted from the emitter 107. The electrons are separated from each other on the gate 105 and are collected by the conductive film 112 of the anode substrate 110 to which the anode voltage VA is applied. In this case, the conductive film 112 is
By collecting the electrons emitted from 07, the phosphor 113 coated on the conductive film 112 can be excited to emit light.

[0011]

By the way, in such an FEC, various power saving means have been considered. For example, on the cathode substrate 100 side: The distance between the gate 105 and the emitter 107 is reduced. 2. A material having a low work function is used as a material for forming the emitter 107. 3. The radius of curvature of the emitter 107 is reduced. 4. Increase emission emission area. And the like.

For example, in the second means, the emitter 107 is made of molybdenum or the like for the reason of workability and the like. This is because the aspect ratio of molybdenum (the height at which the emitter 107 is deposited / the bottom of the emitter 107) is approximately 1: 1 and is therefore a material suitable for manufacturing the emitter 107. However,
Since molybdenum is not a material having a good work function, it is difficult to realize power saving. Also,
For example, when a material having a low work function other than molybdenum is used, there is a problem that workability deteriorates and it becomes difficult to form the emitter 107 into a predetermined shape.

Recently, for example, it has been considered to use diamond-like carbon or the like as an emitter material.
7 is difficult to selectively coat. Therefore, it is particularly difficult to perform the coating after the gate 105 is formed. For this reason, a diode structure is obtained, and low-voltage driving cannot be achieved.
Therefore, it is considered that a specific material is coated on the tip of the emitter 107. However, there is a problem that a gap between the gate 105 and the emitter 107 is narrowed, a short circuit is easily generated, and it is not practical. .

[0014]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and comprises a cathode substrate having a field emission emitter or array formed in a vacuum vessel;
A substrate made of an emitter material, or an anode substrate formed of a thin film or a thick film of the emitter material is arranged to face each other, and a predetermined level of a driving voltage is applied between the cathode substrate and the anode substrate to emit light from the cathode substrate. The electron beam is projected on the anode substrate, and the emitter material is field-deposited on the field emission emitter to manufacture a field emission device.

Further, a cathode substrate and an anode substrate on which a field emission emitter or an array is formed are arranged in a vacuum vessel so as to face each other, and carbonization is performed in a state where a predetermined level of driving voltage is applied between the cathode substrate and the anode substrate. A field emission device is manufactured by introducing a hydrogen-based gas, causing an electron beam emitted from the cathode substrate to strike the anode substrate, and adsorbing ions of the hydrocarbon-based gas to the emitter.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing a state in which a cathode substrate and an anode substrate are arranged to face each other in a vacuum vessel as a manufacturing process of the field emission device of the present embodiment. As shown in FIG. 1, emitters 8, 8, 8,...
A cathode substrate 1 on which a gate 6 and the like are formed, and an emitter material (for example, a C or CH-based mixture or carbide, With the anode substrate 10 on which a thin film or a thick film made of nitride or boride is formed facing each other, the drive voltage VGE and the anode voltage VA
Is applied. At this time, the electrons extracted from the emitters 8, 8, 8... Collide with the anode substrate 1, and the particles of the emitter material beaten out by the collision energy cause the tip portions of the emitters 8, 8, 8. To be deposited. As a result, the emitter material laminated on the anode substrate 10 adheres to the tips of the emitters 8, 8, 8,... By electric field deposition, and coats the surfaces of the emitters 8, 8, 8,.

FIGS. 2A, 2B and 2C are enlarged views of an arbitrary emitter 8 shown in FIG. 1. The manufacturing steps of the field emission device of the present embodiment will be described with reference to these schematic diagrams. explain. The cathode substrate 1 has the same configuration as the cathode substrate 100 previously shown in FIG. 9, and the substrate 2, the cathode 3, the resistance layer 4, the insulating layer 5, the gate 6, the opening 7, and the emitter 8 101, cathode 102, resistance layer 10
3, corresponding to the insulating layer 104, the gate 105, the opening 106, and the emitter 107. Further, in the present invention, a dedicated anode substrate 10 on which no phosphor is formed as described with reference to FIG. 9 in the manufacturing process is used. In this anode substrate 10, the substrate 11 and the conductive film 12 are
11, a film layer 13 made of a low work function emitter material such as C or CH is formed on the surface of the conductive film 12.

As shown in FIG. 2A, the cathode substrate 1 and the anode substrate 10 formed as described above are placed in a vacuum vessel 0 as shown in FIG. And applying the anode voltage VA,
The electron beam emitted from the emitter 8 is irradiated on the anode substrate 10. As a result, due to the energy of the electron beam, heating, and the like, the emitter material forming the film-forming layer 13 evaporates and is ionized by the electron beam from the emitter as shown by the arrow in FIG. Then, as shown in FIG. 2C, the ionized emitter material is selectively subjected to electric field deposition on the tip of the emitter 8, so that the film 9 is selectively formed on the tip of the emitter 8. .

[0019] Incidentally, if the deposition efficiency in depositing the film 9 bad, as indicated arrows in FIG. 1, for example 10 ^-2
It is also possible to activate the deposition by introducing H and / or Ar into the vacuum vessel 0 at 10 to 10 ^-6 Torr. Further, the deposition can be activated by heating the anode substrate 10 from the back surface by, for example, resistance heating, radiant heating, or laser heating. Further, when the film formation layer 13 is made of a conductive emitter material, the film formation layer 13 can also be used as the conductive film 12. Further, as described above, when a C- or CH-based emitter material is used for the film-forming layer 13, the cathode substrate is subjected to laser processing, plasma processing, or the like after the film 9 is formed, so that the diamond-like thin film is formed. If the projections can be changed and a minute projection pattern is formed at the tip of the emitter 8, it is possible to form an emitter that emits an electron beam more stably even at a low vacuum.

In the above-described example, an example in which, for example, a C or CH-based material is used as the film forming layer 13 has been described. However, in addition to this, for example, Cs, Ba, Sr, Ti, Zr, Ca,
Y, Gd, Ce, Nd, Th, Pr, Nb, La, E
It is possible to use u, Ta, T, Hf, and mixtures or carbides or nitrides or borides thereof.

The cathode substrate 1 manufactured through the steps described with reference to FIGS. 2A, 2B, and 2C is
Anode substrate 2 in normal use as shown in (a)
By combining with 0, an FED is formed. The anode substrate 20 corresponds to the anode substrate 110 shown in FIG. 9, and has a conductive film 22 and a phosphor 23 formed thereon. As shown in the figure, when a gate voltage VGE and an anode voltage VA are applied, the phosphor 23 applied to the conductive film 22 is excited to emit light.
FIG. 3 schematically shows the opening 7 enlarged from the front.
As shown in (b), the emitter 8
The film 9 deposited on is observed. When the film 9 is further enlarged, it is observed that the emitter material is coated around the tip of the emitter 8 as shown in FIG.

Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram showing a state in which a cathode substrate and an anode substrate are arranged to face each other in a vacuum vessel as a manufacturing process of the field emission device of the second embodiment. In the second embodiment, as shown in FIG. 4, the cathode substrate 1 and the anode substrate 30 are arranged inside the vacuum vessel 0 so as to face the cathode substrate 1. As an example, a very stable high melting point metal such as W, Ta, Nb or the like is used and, for example, CH ₄ , C
Hydrocarbon gases such as ₂ H ₂ , C ₂ H ₅ OH and CH ₃ OH are introduced at 10 ⁻² to 10 ⁻⁶ Torr. As will be described in detail with reference to FIG. 5, the drive voltage VGE and the anode voltage V
By applying A, ions of the hydrocarbon-based gas are selectively adhered to the tip of the emitter 8, so that a CH-based film is selectively formed at the tip of the emitter 8.

FIGS. 5 (a), 5 (b), and 5 (c) are enlarged views of an arbitrary emitter 8 shown in FIG. 4. According to these schematic diagrams, manufacture of the field emission device according to the second embodiment will be described. The steps will be described. The anode substrate 30 shown in this figure is also a dedicated substrate at the time of manufacturing, like the anode substrate 10, and is composed of the substrate 31 made of a high melting point metal and the conductive film 32 as described above.

The cathode substrate 1 and the anode substrate 30 formed as described above are arranged in a vacuum container 0 as shown in FIG. Introduce a hydrocarbon gas. As a result, the hydrocarbon-based gas introduced into the vacuum vessel 0 is ionized and selectively adheres to the tip of the emitter 8 as shown by the arrow in FIG. Then, as shown in FIG. 5C, a low-carbon (for example, CH-based) film 33 is formed at the tip of the emitter 8. After this, for example, laser heating,
By performing plasma heating or the like, it is possible to change the state to stable diamond-like carbon.

[0025] Figure 6 is a vacuum vessel 0 example 5 × 10 ^-5 as hydrocarbon gas (vacuum chamber) shown in FIG. 4 CH
_{FIG. 4} is a graph showing the relationship between the gate voltage and the anode current (the amount of emitted electrons) when ₄ is introduced, in which the vertical axis represents the anode current and the horizontal axis represents the gate voltage. In addition, white ○ mark is CH ₄ prior to the introduction, a black circle ● mark the time of CH ₄ introduction, white □ marks indicate the post-CH ₄ introduction. As shown in the figure, when CH ₄ is introduced into the vacuum vessel 0, the amount of emitted electrons is smaller than that before the introduction of CH ₄ when the same level of gate voltage is applied, as indicated by a black circle ●. It can be seen that has increased. Further, it can be seen that the emission of electrons is further increased after the introduction of CH ₄ . Therefore, CH
_It can be said that the film 33 is formed on the emitter 8 by the introduction of _{4, and the} electron emission efficiency of the emitter 8 is improved.

FIG. 7 shows a restored state of the emission when CH ₄ is introduced into the vacuum vessel 0 and thereafter CH ₄ is stopped and the gate voltage and the anode voltage are simply applied. Current (amount of emitted electrons), C on the horizontal axis
The time course of H ₄ introduction (every 30 minutes) is shown. In the horizontal axis of FIG. 7, the “1.0” point is before introducing CH ₄ (Before).
The “0” point is also restored to the degree of vacuum before introducing (Before) again after introducing each gas pressure of 5 × 10 ⁻⁴ Torr (gas pressure in terms of N ₂ gas). Is the emission value immediately after This figure shows the history of emissions for three hours after gas introduction. From the values shown in the figure, it can be seen that the effect of each gas on the emission is different. That is, in the vacuum vessel 0, the time and the degree of the recovery of the emission are determined by the state in which the emitter 8 is exposed to each gas.

FIG. 8 is a graph showing the relationship between the anode current and the temperature in the vacuum vessel 0 when the film 33 is selectively formed at the tip of the emitter 8 with CH ₄ .
The vertical axis indicates the anode current, and the horizontal axis indicates the temperature. As shown, when the film 33 is formed in a state where the temperature in the vacuum chamber 0 is set to, for example, normal temperature (for example, about 22 to 23 °), the anode current becomes about 150 to 200 μA
Becomes However, when the temperature of the vacuum vessel 0 is set to, for example, about 100 ° and the film 33 is formed, the anode current becomes, for example, about 1200 μA. That is, in the state shown in FIG. 4 in which the temperature inside the vacuum vessel 0 is set to, for example, 100 ° C. or more, the gate voltage VGE and the anode voltage VA are applied to form the film 33, so that a more efficient electric field is formed. An emission element can be manufactured.

[0028]

As described above, the first aspect of the present invention is as follows.
A film layer made of a low work function emitter material is formed in a vacuum vessel, an anode substrate and a cathode substrate are arranged, and the film layer is field-deposited on the tip of the emitter of the cathode substrate. Similarly, in the vacuum vessel, an anode substrate and a cathode substrate having substantially the same structure as a normal anode substrate are arranged, and for example, a hydrocarbon-based gas is introduced in a state where a gate voltage and an anode voltage are applied, whereby carbonization is performed. Hydrogen-based gas ions can be selectively adsorbed to the tip of the emitter. As a result, the tip of the emitter can be covered with a film having a low work function, and the efficiency of field emission can be improved. Furthermore, in the case of electric field deposition, by using a material such as C or CH as an emitter material, a film is formed at the tip of the emitter, and then the shape is changed to a diamond-like thin film by laser heating or plasma heating, so that the field emission is more stable. It is also possible to make it. Therefore, according to the present invention, by covering the tip of the emitter with a film having a low work function, a field emission device capable of performing stable field emission even at a low vacuum degree can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state in which a cathode substrate and an anode substrate are arranged in a vacuum vessel as a method for manufacturing a field emission device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating steps of a method for manufacturing a field emission device according to an embodiment.

FIG. 3 is a diagram illustrating an FEC formed by the method for manufacturing a field emission device according to the embodiment.

FIG. 4 is a view showing a state in which a cathode substrate and an anode substrate are arranged in a vacuum vessel as a method for manufacturing a field emission device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating steps of a method for manufacturing a field emission device according to a second embodiment.

FIG. 6 is a diagram illustrating a relationship between a gate voltage and an anode current when a hydrocarbon-based gas is introduced in the method for manufacturing a field emission device according to the second embodiment.

FIG. 7 is a diagram illustrating a state of restoring the emission when the introduction of the hydrocarbon-based gas is stopped and the electricity is simply supplied in the method of manufacturing the field emission device according to the second embodiment.

FIG. 8 is a diagram illustrating emission efficiency depending on the temperature in a vacuum vessel during manufacturing in the method for manufacturing a field emission device according to the second embodiment.

FIG. 9 is a sectional view showing a conventional field emission device.

FIG. 10 is a perspective view showing a conventional field emission device.

[Explanation of symbols]

 Reference Signs List 1 cathode substrate 8 emitter 10, 30 anode substrate 13 film-forming layer 9, 33 film

Claims (6)

[Claims] A cathode substrate on which a field emission emitter or an array is formed, and a substrate made of an emitter material, or an anode substrate made of a thin film or a thick film of the emitter material, are arranged in a vacuum vessel so as to face each other; A driving voltage of a predetermined level is applied between a cathode substrate and an anode substrate to cause an electron beam emitted from the cathode substrate to project on the anode substrate, and the emitter material is field-deposited on the field emission emitter. Method of manufacturing a field emission device. 2. The field emission device according to claim 1, wherein H and / or Ar is introduced into the vacuum vessel at 10 ^{−2 to} 10 ⁻⁶ Torr while the driving voltage is applied. Manufacturing method. 3. The method for manufacturing a field emission device according to claim 2, wherein the anode substrate is subjected to resistance heating, radiation heating, or laser heating from the back surface while the drive voltage is applied. 4. A cathode substrate and an anode substrate on which a field emission emitter or an array is formed are arranged in a vacuum vessel so as to face each other, and carbonization is performed in a state where a predetermined level of drive voltage is applied between the cathode substrate and the anode substrate. A hydrogen-based gas is introduced, an electron beam emitted from the cathode substrate is projected on the anode substrate, and ions of the hydrocarbon-based gas are adsorbed on the emitter. Production method. 5. The method according to claim 1, wherein the hydrocarbon gas is placed in a vacuum vessel.
6. The method according to claim 5, wherein the introduction is carried out at 0 ^-2 to 10 ^-6 Torr.
3. The method for manufacturing a field emission device according to claim 1. 6. The method for manufacturing a field emission device according to claim 5, wherein after the ions of the hydrocarbon gas are adsorbed, laser processing or plasma processing is performed on the surface of the emitter. .