JP2002367555A - Vacuum device made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum device made of an aluminum alloy having a high ionization efficiency and achieving high exhaust rate. SOLUTION: The vacuum device made of an aluminum alloy includes a vacuum container made of the aluminum alloy formed with cathodes 36 packed in pores 35 in an anodic oxide film 33 formed on the vacuum side surface of the vacuum container, and also with extraction electrodes 37 provided on the surface of the anodic oxide film, the cathodes emitting electrons upon field emission; cathode terminals for applying voltages to the cathodes; extraction electrode terminals for applying voltages to the extraction electrodes; and a driving power source for applying voltages to both poles of the cathodes and the extraction electrodes. The cathode is made of a magnetic material magnetized in the longitudinal direction of the pores. In place of the magnetized cathodes, the extraction electrode 37 may be in the form of a circumferentially formed coil to produce a magnetic field in the direction of the axis of the vacuum container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum apparatus used in a vacuum heat treatment furnace, various analyzers, accelerators, semiconductor manufacturing apparatuses, and the like. Related to the device.

[0002]

2. Description of the Related Art Conventionally, a vacuum apparatus as shown in FIG. 6 has been proposed as a vacuum apparatus for improving the efficiency of an exhaust function (Japanese Patent Laid-Open No. 10-228880). FIG. 6 is a perspective view of a cross section showing a conventional aluminum alloy vacuum device. In the figure, 1 is a base, 2 is an insulator, and 3 is a vacuum vessel made of an aluminum alloy. The vacuum vessel 3 made of an aluminum alloy is composed of a base 31 made of an aluminum alloy, and the inner and outer peripheral surfaces are subjected to anodizing treatment to form anodized films 33 and 34. FIG. 7 shows an enlarged view of the anodic oxide film 33 (part A in FIG. 6) applied on the vacuum side. The anodic oxide film 33 is formed on the vacuum side of the barrier layer 32 on the vacuum side of the substrate 31. In the fine holes 35 present in the anodic oxide film 33, metallic iron is deposited as an electrode material for emitting electric field and used as a negative electrode 36. Further, on the vacuum side of the anodic oxide film 33,
A conductive extraction electrode 37 is provided on the entire surface. The extraction electrode 37 extracts electrons emitted from the negative electrode 36. A negative electrode terminal 41 for applying a voltage to the negative electrode 36 and a lead electrode terminal 42 are provided. In addition,
The lead electrode terminal 42 is provided insulated from the base 31 and the like. Negative electrode terminal 41 and lead electrode terminal 4
2 is connected to a drive power supply 61 so that a potential can be applied. Further, an ion electrode 5 for collecting ions is arranged near the exhaust port in the vacuum vessel 3 made of aluminum alloy, and a power supply 62 for the ion electrode for driving the ion electrode is arranged. The negative electrode terminal 41 for applying a drive voltage to the negative electrode 36 and the extraction electrode terminal 42 are connected to a drive power supply 61.
It is connected to the. Negative electrode 36 and extraction electrode 37
When a voltage is applied from the drive power supply 61 to the electrode, the residual gas in the vacuum device is ionized by electrons emitted from the negative electrode 36 formed in the fine holes of the anodic oxide film 33 formed on the vacuum side. The ions are guided to the ion electrode 5 provided near the exhaust port by the force of the electric field to accelerate the exhaust.

[0003]

However, in the conventional vacuum device, the electrons emitted from the negative electrode travel straight toward the electrode arranged near the exhaust port. Accordingly, the probability of collision with gas is low because the flight distance is short. Therefore, the number of electrons contributing to ionization was small. In order to improve the efficiency of ionization, a combination of emitted electrons and a magnetic field can be considered. This causes rotational movement of the emitted electrons as they traverse the magnetic field, increasing the flight distance, increasing the probability of collision with the gas and promoting ionization. As a method of applying a magnetic field, a method in which a magnetic field generating coil is provided around a vacuum vessel is considered. However, the device becomes large and handling becomes inconvenient. For example, when used as a vacuum chamber, objects are put in and out of vacuum. At that time, if the coil is around the vacuum device, it becomes an obstacle and the operation becomes inconvenient. Further, when the barrier layer is sufficiently thick, the MIM (Metal-Insu
Because it has a lator-metal structure, only a very small amount of current can be obtained, and in order to obtain a sufficient current, the extraction voltage must be extremely high, and the practicality is extremely narrow. Accordingly, an object of the present invention is to provide an aluminum alloy vacuum device having a high ionization efficiency and a high pumping speed by devising a method of applying a magnetic field and a layer structure around a negative electrode.

[0004]

In order to solve the above-mentioned problems, the present invention relates to a negative electrode which fills fine holes of an anodic oxide film formed on the vacuum side surface of a vacuum vessel and emits electrons by electric field radiation. An aluminum alloy vacuum vessel in which an extraction electrode provided on the surface of the anodic oxide film is formed, a negative electrode terminal for applying a voltage to the negative electrode, and an extraction electrode terminal for applying a voltage to the extraction electrode. In a vacuum apparatus made of an aluminum alloy having a driving power supply for applying a voltage to both of the cathode and the extraction electrode, the cathode is made of a magnetic material magnetized in the length direction of the fine holes. With this configuration, when electrons emitted from the tip of the negative electrode cross the magnetic field, the electrons rotate by cyclotron motion, so that the probability of collision with the residual gas increases as compared with straight-ahead electrons, and therefore, the pumping speed improves. Further, the extraction electrode may have a coil-shaped configuration formed in a circumferential direction so as to generate a magnetic field in a central axis length direction of the aluminum alloy vacuum vessel. With this configuration, when a current flows through the extraction electrode, the emitted electrons receive the Lorentz force and fly in a direction substantially perpendicular to the magnetic field, and thus have a longer trajectory than when no magnetic field is generated. . That is, the probability of collision with gas molecules to be evacuated and the like existing in the vacuum vessel and ionization increases. Further, as the number of ionized gas molecules increases, molecules in the vacuum vessel move to the exhaust port and are quickly exhausted. Further, by making the barrier layer in contact with the negative electrode terminal extremely thin, the amount of emitted electrons increases, so that the molecular weight of the ionized gas to be exhausted increases, and the above-described effect is further improved, and the exhaust becomes faster.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail with reference to the drawings shown in the embodiments. (First Embodiment) FIG. 1 shows a first embodiment of the present invention. FIG.
FIG. 2 is a schematic diagram in which the negative electrode portion of the present invention is enlarged. In the figure, 36 is a negative electrode, and 37 is an extraction electrode. Other symbols are the same as those of the conventional aluminum alloy vacuum device. Base 31 of aluminum alloy vacuum vessel 3
Is made of duralumin and has an alumite treatment on the inner and outer peripheral surfaces. The negative electrode 36 in the anodic oxide film 33 is formed by depositing cobalt as a ferromagnetic material so that it becomes a permanent magnet that generates a magnetic field in the length direction of the fine holes 35.
The anodic oxide film 33 and the negative electrode 36 were formed by the following method. (1) A portion to be alumite-treated is immersed in a 15% by weight sulfuric acid solution at a solution temperature of 20 ° C. and a current density of 1.5 A / dm 2, 15
Anodizing was performed for minutes. The thickness of the anodic oxide film 33 is 10
μm, and the diameter of the fine holes 35 was 300 Å. (2) Next, 2% -H3 was added to 5% -CoSO4.H2O.
The solution of BO3 was adjusted to pH 6.0, and an alternating current of 15 V and 50 Hz was applied for about 10 minutes while stirring to deposit metallic cobalt. (3) On the anodic oxide film 33 on the inner peripheral surface, an extraction electrode 37 was formed by wire explosion spraying of Al in vacuum. (4) After the extraction electrode was prepared, the negative electrode 36 was magnetized by approaching a permanent magnet made of rare earth. The arrow in the figure indicates the direction of magnetization. The vacuum vessel 3 made of the aluminum alloy thus produced
Was placed on the insulator 2 provided on the gantry 1 to assemble the evacuation apparatus. A rotary pump and a turbo molecular pump were used as the exhaust pump. Next, the performance of the vacuum apparatus of the present invention was examined based on the pumping speed. For comparison, a vacuum vessel 3 made of an aluminum alloy and having the same volume as that of the prior art and subjected to only alumite treatment was added. The driving conditions were such that the potential difference between the extraction electrode 37 and the negative electrode 36 was 60 V, and 600 V was applied to the ion electrode 7 near the exhaust port. The result is shown in FIG. The evacuation time to reach the target pressure is several times faster in the present embodiment than in the conventional example, and it can be seen that there is an excellent effect. This is presumably because the magnetic field leaking from the tip of the negative electrode 36 causes electrons also emitted from the tip to generate cyclotron motion and collide with the residual gas generated from the wall of the vacuum vessel to be ionized, thereby increasing the exhaust speed. . In addition, since the negative electrode itself forms a part of a structure for generating a magnetic field, there is also an effect that it is not necessary to separately and precisely position a magnet or the like near each negative electrode. Since the magnetic field can be formed without using a magnetic field generating device such as a coil, the size of the device can be reduced. In this embodiment, cobalt is used as the material of the negative electrode. However, the present invention is not limited to this, and any material that generates a magnetic field, such as nickel-cobalt, can provide the same effect.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
Shown in FIG. 3 is a perspective view of a cross section of a vacuum apparatus showing a second embodiment of the present invention, and FIG. 4 is an enlarged schematic view of a portion (A portion) of an extraction electrode. In the figure, reference numeral 37 denotes an extraction electrode formed in a coil shape. Other symbols are the same as those of the conventional aluminum alloy vacuum device. The base 31 of the aluminum alloy vacuum vessel 3 is made of an aluminum alloy of A5052. The thicknesses of the anodic oxide coatings 33 and 34 applied to the inner and outer peripheral surfaces were 10 μm, and the diameter of the fine holes 35 was 300 Å. The material of the cathode 36 is metallic iron. The coiled extraction electrode 37 was formed as follows. (1) An iron coil having a diameter larger than the inner diameter of the vacuum vessel 3 was fixed to the inner wall of the vacuum vessel 3 so as to form a spiral. Since the iron coil has a spring property and a restoring force to the outside, it is fixed to the inner wall and functions as a mask. The number of coil turns was 500 turns. (2) Aluminum was subjected to wire explosion spraying in a vacuum to form an aluminum film on the surface of the anodic oxide film thickness 33 and the surface of the iron coil. (3) The iron coil was removed to form a coiled extraction electrode 37. The aluminum alloy vacuum container 3 thus manufactured
Was placed on the insulator 2 provided on the gantry 1 to assemble the evacuation apparatus. A rotary pump and a turbo molecular pump were used as the exhaust pump. Next, the performance of the vacuum apparatus of the present invention was examined based on the pumping speed. The potential difference between the extraction electrode 37 and the negative electrode 36 was set to 60V. The direction of the magnetic field was such that the exhaust port side was the N pole, and the magnetic field at the center of the aluminum alloy vacuum vessel 3 was 100 to 300 Oe. Note that 600 V was applied to the ion electrode 7 near the exhaust port. For comparison, a vacuum vessel 3 made of an aluminum alloy of A5052 having the same volume as that of the prior art and subjected to only alumite treatment was added. The result is shown in FIG. The evacuation time to reach the target pressure was several times faster in the present example than in the conventional example, and it was found that there was an excellent effect. Since the extraction electrode has a coil shape, a magnetic field is generated in the direction of the central axis of the vacuum device when a current is applied to the extraction electrode. In that state, electrons are emitted into a vacuum. Since the direction of the magnetic field is substantially perpendicular to the moving direction of the field-emitted electrons, the electrons receive a force due to the Lorentz force, and have a longer trajectory than when no magnetic field is generated. Therefore, the probability of collision and ionization with gas molecules to be evacuated existing in the vacuum vessel increases, and ionized gas molecules increase. Become. In addition, since the extraction electrode is used in combination with the magnetic field generating coil, there is no need to prepare a separate coil, and since the coil is formed in close contact with the inside of the vacuum vessel, it hinders operation around the vacuum vessel. It also has features that do not have to be. (Third Embodiment) A third embodiment of the present invention will be described.
The structure of the vacuum device of the present embodiment is the same as that of the first embodiment in both the appearance and the sectional structure. The difference is that the thickness of the barrier layer 32 is 10 nm. For comparison, a substrate having a conventional barrier layer having a thickness of 100 nm was prepared. Exhaust driving was performed in the same manner as in the first embodiment, and the exhaust characteristics were compared. As a result, it was found that the pump of the present embodiment improved the pumping speed by about 10 times compared to the conventional pump, which was a good result. (Fourth Embodiment) A fourth embodiment of the present invention will be described.
The structure of the vacuum apparatus of the present embodiment is the same as that of the second embodiment in both appearance and cross-sectional structure. The difference is that the thickness of the barrier layer 32 is 1 nm or less. For comparison, a substrate having a conventional barrier layer having a thickness of 100 nm was prepared. Exhaust driving was performed in the same manner as in the second embodiment, and the exhaust characteristics were compared. As a result, it was found that the pump of the present embodiment improved the pumping speed by about 70 times as compared with the conventional pump, which was a good result.

[0007]

As described above, according to the present invention, since the magnetic field is applied by using the magnetic material in which the cathode is magnetized in the longitudinal direction of the fine holes, the probability of collision between gas and electrons is increased. This has the effect of obtaining a vacuum device made of an aluminum alloy with a high evacuation speed that can obtain an ultra-high vacuum in a short time. In addition, the extraction electrode was formed in the shape of a coil formed in a circumferential direction so as to generate a magnetic field in the central axis length direction of the aluminum alloy vacuum vessel, and a voltage was applied to the coil to generate a magnetic field. In the same way as described above, the probability of collision between gas and electrons increases, ionization is promoted, and the gas is quickly exhausted by the electric field of the electrode provided at the exhaust port. is there. Further, by setting the barrier layer between the cathode and the cathode terminal for applying a voltage to the cathode to 10 nm or less, the amount of electrons emitted from the cathode increases, so that the ionized gas molecules to be exhausted increase. In addition, the gas attached to the negative electrode can be sufficiently blown, and the evacuation speed of the vacuum device can be further remarkably improved. Also, in any means, the magnetic field can be formed without using a separate magnetic field generator such as a coil, so that the size of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic diagram of a negative electrode according to a first embodiment of the present invention.

FIG. 2 is a graph showing the exhaust characteristics of the vacuum device in the first embodiment.

FIG. 3 is a perspective view of a cross section of a vacuum apparatus showing a second embodiment of the present invention.

FIG. 4 is a partially enlarged schematic view of an extraction electrode in a second embodiment.

FIG. 5 is a graph showing the exhaust characteristics of the vacuum device in the second embodiment.

FIG. 6 is a perspective view of a cross section showing a conventional vacuum vessel.

FIG. 7 is an enlarged schematic view of a portion of a conventional extraction electrode.

[Explanation of symbols]

1: Stand 36: Negative electrode 2: Insulator 37: Extraction electrode 3: Vacuum container 41: Terminal for negative electrode 31: Base 42: Terminal for extraction electrode 32: Barrier layer 5: Ion electrode 33: Anodized film (vacuum side) 6) Drive power supply 34: Anodized film (atmosphere side) 35: Micropore

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuhiko Ota 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Inside (72) Inventor Shinji Shinbe 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture No. Yaskawa Electric Co., Ltd. F-term (reference) 5C038 AA03

Claims (3)

[Claims] 1. A negative electrode which is filled in micropores of an anodic oxide film formed on the vacuum side surface of a vacuum vessel and emits electrons by electric field radiation, and an extraction electrode provided on the surface of the anodic oxide film are formed. Aluminum alloy vacuum vessel, a negative electrode terminal for applying a voltage to the negative electrode, an extraction electrode terminal for applying a voltage to the extraction electrode, and applying a voltage to both the negative electrode and the extraction electrode. An aluminum alloy vacuum device having a driving power supply, wherein the negative electrode is made of a magnetic material magnetized in a length direction of the fine hole. 2. A negative electrode, which is filled in micropores of an anodic oxide film formed on the vacuum side surface of a vacuum vessel and emits electrons by electric field radiation, and an extraction electrode provided on the surface of the anodic oxide film, are formed. Aluminum alloy vacuum vessel, a negative electrode terminal for applying a voltage to the negative electrode, an extraction electrode terminal for applying a voltage to the extraction electrode, and applying a voltage to both the negative electrode and the extraction electrode. In the aluminum alloy vacuum device having a driving power supply, the extraction electrode has a shape of a coil formed in a circumferential direction so as to generate a magnetic field in a central axis length direction of the aluminum alloy vacuum container. A vacuum device made of an aluminum alloy, characterized by the following. 3. The aluminum alloy vacuum apparatus according to claim 1, wherein the thickness of the barrier layer between the cathode and the cathode terminal is set to 10 nm or less.