JP2000180599A - Electron beam processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce the loss of an electron beam due to the collision of it with an inflow gas and the scattering of it by forming a concave part near a beam passage hole in the structure of a section including a beam passage part in a decompression chamber adjoining an atmospheric pressure chamber. SOLUTION: Decompression chambers 3, 4 and 5 and electron beam chambers 6 and 7 are located adjacently to an atmospheric pressure chamber 2 one by one, the decompression chambers 3, 4 and 5 and the electron beam chamber 6 are connected with exhaust ports 31, 41, 51 and 61 respectively and an air is exhausted by a group of vacuum pumps. Small openings 8, 9, 10 and 11 through which a beam passes are formed in diaphragms in adjoining spaces of each of the decompression chambers 3, 4 and 5 and the electron beam chamber 6, and staggered exhaust is carried out in the openings 8, 9, 10 and 11 to reduce pressure from the atmospheric pressure chamber 2 to the electron beam chamber 7 in order. The structure of a section including a beam passage part of the decompression chamber 3 is made so as to form a concave part 12 near the opening 9. Consequently, the passage distance of an electron beam in the decompression chamber 3 can be infinitely shortened in theory, which can restrain the collision of the electron beam with a gas flowing in from the atmospheric pressure chamber 2 and the scattering of the electron beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various chemical reactions by irradiating an object with an electron beam to decompose or excite a part of chemical bonds of the object to generate active species (radicals). And an electron beam processing apparatus for processing an object to be processed.

[0002]

2. Description of the Related Art In an "irradiation method for gaseous substances by an electron beam" disclosed in Japanese Patent Application Laid-Open No. 53-88656, electrons generated by heating a metal such as tungsten and the like are accelerated by an electric field. An electron beam generator for directly irradiating a beam to be processed, such as exhaust gas, in an irradiation container from a minute opening is described.

[0003] Further, in an "apparatus for purifying exhaust gas containing sulfur and nitrogen" disclosed in Japanese Patent Application Laid-Open No. 62-14921, an electron beam passes through electron beam passage holes provided in each partition of a multistage decompression chamber. There is described a purification apparatus for irradiating an object to be processed such as exhaust gas in an irradiation container.

[0004]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. Sho 53-88656
In the technique disclosed in Japanese Patent Application Laid-Open Publication No. H11-260, an electron beam chamber for generating an electron beam and an atmospheric pressure chamber (reaction chamber) which is a container for an object to be processed such as exhaust gas are adjacent to each other. Is very difficult to maintain. Incidentally, the generation and maintenance of the electron beam requires a reduced pressure (vacuum state) where the gas pressure in the space is about 0.01 Pa or less, and the atmospheric pressure (about 100000 P
a) there is a 7-digit pressure difference. As means for constantly maintaining the pressure difference, a multi-stage decompression chamber partitioned by a partition having a small opening as an electron beam passage hole is provided as disclosed in Japanese Patent Application Laid-Open No. Sho 62-14921, It is conceivable to reduce the load on the exhaust system by providing an exhaust system for each decompression chamber and dividing the differential pressure stepwise.

However, in this case, even in the decompression chamber, especially in the decompression chamber adjacent to the atmospheric pressure chamber, the electron beam may collide with the gas flowing from the atmospheric pressure chamber and cause scattering or the like. Cannot be introduced into the atmospheric pressure chamber through a minute opening provided in a partition wall between the atmospheric pressure chamber and the atmospheric pressure chamber, and it is not considered that there is a loss. Also, in some cases, the initially provided small opening is deformed into a larger opening by an electron beam that is larger than the initial opening diameter due to collision and scattering with the inflow gas, and as a result, the load on the vacuum exhaust system is reduced. There is a problem that the required vacuum state cannot be maintained.

An object of the present invention is to provide an electron beam processing apparatus having a multistage decompression chamber and a respective exhaust system capable of withstanding practical use, wherein electron beam loss due to collision and scattering with gas flowing in from an atmospheric pressure chamber is reduced. It is to provide a device.

[0007]

In order to achieve the above object, an electron beam processing apparatus includes an electron beam source, which draws an electron beam from an electron beam source into an electron beam chamber and narrows the electron beam to a predetermined beam diameter at a predetermined position by a beam focusing optical system. Each of the multi-stage decompression chambers provided with an exhaust system is passed through an electron beam passage hole provided in each partition and introduced into the atmospheric pressure chamber, and irradiated to the object in the atmospheric pressure chamber. The cross-sectional structure including the beam passage portion of the adjacent first decompression chamber has a structure in which a concave portion is formed near the beam passage hole.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electron beam processing apparatus according to the present invention will be described based on the illustrated embodiment.

FIGS. 1 and 2 show an embodiment of the present invention. In FIG. 1, the configuration of the electron beam processing apparatus 1 is as follows. The atmospheric pressure chamber 2 is a reaction chamber in which an exhaust gas or the like as an object to be processed is introduced and processed. The first decompression chamber 3 is adjacent to the atmospheric pressure chamber 2, the second decompression chamber 4 is adjacent to the first decompression chamber 3, and is on the opposite side of the atmospheric pressure chamber 2, and is adjacent to the second decompression chamber 4. An electron beam chamber 6 is arranged adjacent to the third decompression chamber 5 and the third decompression chamber 5, and an electron beam source 7 is arranged adjacent to the electron beam chamber 6. These multi-stage decompression chambers 3, 4, 5
And the electron beam chamber 6 has exhaust ports 31 and 4 respectively.
1, 51 and 61, each of which is evacuated by a vacuum pump group (not shown) having a function of an appropriate operating pressure and an evacuation speed. Atmospheric pressure chamber 2, multi-stage decompression chambers 3, 4,
5. Small apertures 8, 9, 10, and 11 having a diameter of several mm or less are provided as partition holes for electron beams in partition walls of adjacent spaces of the electron beam chamber 6, respectively.
These openings 8, 9, 10, and 11 have sufficiently small conductances when evacuated by a vacuum pump.
Differential exhaust that generates a large differential pressure on both sides is realized. By selecting and arranging the appropriate type of vacuum pump for evacuating each decompression chamber (differential exhaust chamber) and the electron beam chamber, and the capacity such as the exhaust speed, the pressure is sequentially increased from the atmospheric chamber to the electron beam chamber. Is lowering.

In such a configuration, the cross-sectional structure including the beam passage portion of the first decompression chamber 3 forms a concave portion 12 (a convex portion in the second decompression chamber side) near the beam passage hole. It has become. Here, the electron beam generating means comprises an electron beam source 7 for generating plasma as shown in JP-A-8-222173, an electron beam extraction electrode 13, an electron beam chamber 6, and the like. As means for focusing the electron beam to a predetermined position along the traveling path of the electron beam 14 from the electron beam source 7 to the atmospheric pressure chamber 2 through the electron beam chamber 6, the multi-stage decompression chambers 5, 4, and 3, an electrostatic lens or the like is used. A beam focusing optical system such as a magnetic lens is provided. The electrostatic lens includes an electrostatic lens electrode 15 and a DC high voltage power supply (not shown), and the magnetic lens includes solenoid coils 16a and 16a.
b, 16c and a DC current source (not shown).

In such a configuration, the electron beam 14 extracted from the electron beam source 7 to the electron beam chamber 6 and accelerated at the same time as being accelerated is appropriately focused by the above-mentioned beam focusing optical system and provided on the partition wall of each decompression chamber. After passing through the openings 11, 10, 9, 8 as electron beam passage holes, it is introduced into the atmospheric pressure chamber 2. The electron beam that has entered the atmospheric pressure chamber 2 forms a cloud-like active region (electron cloud 17) while repeatedly colliding and scattering with exhaust gas or the like, which is an object to be processed. The size of the electron cloud 17 is determined by the acceleration energy of the electron beam. For example, the penetration distance (range) of electrons into one atmosphere of air (density 1 kg / m ³ ) is determined by the energy of the electron beam being 200 k.
It is known to be about 44 cm at eV and about 4 m at 1 MeV. In FIG. 1, the electron beam 14 is applied to the atmospheric pressure chamber 2 from both sides.
Has been introduced to expand the processing area.

FIG. 2 is an enlarged view of the first decompression chamber 3 of FIG. When the first decompression chamber 3 is configured as described above, the electron beam passage distance L in the first decompression chamber can be reduced in principle to infinity, and the electron beam is supplied from the atmospheric pressure chamber 2 to the inflow gas. It can be expected that collision and scattering will be suppressed. However, the beam passage distance L
Is extremely undesirable because the conductance of the exhaust system of the decompression chamber 3 itself becomes small and the load on the exhaust system becomes large. Therefore, in reality, the beam passage distance L is set to be as small as possible within a range that does not impose a load on the exhaust system of the first decompression chamber. According to the inventors of study results, specifically 0.3~0.5mm a diameter d ₀ of the minute aperture 8 between the atmospheric pressure chamber, the first vacuum chamber, first, the opening between the second pressure reduction chamber The diameter d1 of _No. 9 was set to 3 to 5 mm, and the beam passing distance L was selected to be ₁₀ to 30 mm. Solenoid coil 16a
Axial width dimension W of, considering that it is usually about 50 to 80 mm, as the relationship between the dimensions, the beam passing distance L is sufficiently smaller than W, it is possible that sufficiently larger than the opening diameter d _1. In this way, in the first decompression chamber, the electron beam hardly scatters or diverges due to collision with the gas in the passage of the electron beam, so that the beam can be narrowed down to a predetermined beam diameter by the beam focusing optical system. This has the effect that no loss is caused. Also, since the electron beam does not spread beyond the opening diameter of the initially provided beam passage hole, the periphery of the opening is damaged by irradiation of the electron beam around the opening, the opening is enlarged, and the load on the vacuum exhaust system is increased. Is increased, and a stable evacuation system is maintained without a loss of stable operation.

So far, only the first decompression chamber has been described, but on the second decompression chamber and on the higher vacuum side, the gas pressure in each decompression chamber is reduced by one to several orders of magnitude from the first decompression chamber. Therefore, even if the electron beam passage distance in each of the decompression chambers is longer than the beam passage distance in the first decompression chamber by one digit or more, it may not be possible.

In FIG. 2, the volume of the first decompression chamber 3 can be made sufficiently large irrespective of the reduction of the beam passing distance L. The first decompression chamber is a vacuum evacuation system for directly evacuating it. From the point of view, it becomes a decompression chamber with little pressure fluctuation,
Stable operation of the system can be ensured. By the way, the minute opening 8 in the partition wall between the atmospheric pressure chamber and the first decompression chamber is disclosed in JP-A-8-2.
As described in Japanese Patent No. 22173, the electron beam 14 is formed from the viewpoint of alignment. From the viewpoint of reducing the load on the exhaust system, it is desirable that the aperture diameter be as small as possible within a range in which a required beam current can be passed. In this embodiment, the magnetic lens solenoid coil 16a for narrowing the beam at the minute opening provided in the partition between the first decompression chamber and the atmospheric pressure chamber can be arranged sufficiently close to the minute opening. A magnetic lens having a short focal length can be formed, and there is an effect that the diameter of the opening 8 to the partition wall between the atmospheric pressure chamber and the first decompression chamber can be easily reduced.

FIG. 3 shows another embodiment of the present invention, which corresponds to the first decompression chamber 3 in FIG. Here, the shape in the vicinity of the electron beam passage hole 9 is a conical shape toward the atmospheric pressure chamber 2. With such a shape, there is an effect that both the reduction of the beam passage distance L and the increase in the conductance of the exhaust of the decompression chamber 3 itself are further improved.

FIG. 4 shows another embodiment according to the present invention. In the present embodiment, the beam focusing optical system (solenoid coil 16 of the magnetic lens) closest to the atmospheric pressure chamber 2 is the second
It is installed in the decompression chamber 4. Also in this embodiment, the first
The electron beam passing distance L in the decompression chamber can be shortened, and loss of the electron beam due to scattering or the like can be reduced. Second
Since the space near the shaft in the decompression chamber can be made sufficiently large, the conductance of the exhaust system of the second decompression chamber itself can be made large, and the load on the vacuum pump in this exhaust system can be reduced.

FIG. 5 shows still another embodiment according to the present invention. In this embodiment, a beam focusing optical system (solenoid coil 16) closest to the atmospheric pressure chamber 2 is installed in the third decompression chamber 5, and the concave portion 12 a for the first decompression chamber 3 and the second
A concave portion 12b for the decompression chamber 4 is formed. With such a configuration, the electron beam passage distances L ₁ and L ₂ of the first decompression chamber 3 and the second decompression chamber 4 are shortened within a range that does not impair the conductance of each decompression chamber to the exhaust system. be able to. Therefore, loss due to scattering of the electron beam in the first decompression chamber 3 can be suppressed. Further, in view of the operation principle of the multistage differential pumping, the opening diameters d ₀ , d ₁ , d ₂ of the electron beam passage holes 8, 9, 10 can be set so as to gradually increase from the atmospheric pressure chamber side. Considering that the sum (L ₁ + L ₂ ) of the beam passing distances of the first and second decompression chambers can be set small as described above, the multistage decompression chambers 5 and 5 can be formed by a single magnetic lens.
A magnetic field lens having a short focal length ranging from 4 to 3 can be formed to converge an electron beam and reduce the number of components.

[0018]

According to the electron beam processing apparatus of the present invention described above, the electron beam passing distance in the first decompression chamber adjacent to the atmospheric pressure chamber can be shortened. There is an effect that beam loss can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an electron beam processing apparatus according to one embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of a first decompression chamber according to one embodiment of the present invention.

FIG. 3 is an enlarged view of the vicinity of a first decompression chamber according to another embodiment of the present invention.

FIG. 4 is an enlarged view of the vicinity of a first decompression chamber according to another embodiment of the present invention.

FIG. 5 is an enlarged view of the vicinity of first to third decompression chambers according to another embodiment of the present invention.

[Explanation of symbols]

1. Electron beam processing device, 2. Atmospheric pressure chamber (reaction chamber),
3, 4, 5 ... decompression chamber (differential exhaust chamber), 6 ... electron beam chamber, 7 ... electron beam source, 8, 9, 10, 11 ... electron beam passage hole (opening), 12 ... recess, 13 ... extraction Electrode, 1
4 electron beam, 15 electrostatic lens electrode, 16 solenoid coil, 17 electron cloud, 31, 41, 51, 61
exhaust port.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Minoru Suzuki 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant, Hitachi, Ltd. (72) Hirofumi Seki 7-2, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 Inside Power & Electric Development Division, Hitachi, Ltd.

Claims (2)

[Claims] An electron beam drawn from an electron beam source into an electron beam chamber is narrowed down to a predetermined beam diameter at a predetermined position by a beam focusing optical system, and each of the electron beams is applied to each partition of a multistage decompression chamber having an exhaust system. In an electron beam processing apparatus, which passes through an electron beam passage hole provided and is introduced into an atmospheric pressure chamber and irradiates an object to be processed in the atmospheric pressure chamber, a beam passing portion of a first decompression chamber adjacent to the atmospheric pressure chamber is used. The cross-sectional structure including
An electron beam processing apparatus having a structure in which a concave portion is formed near a beam passage hole. 2. The system according to claim 1, wherein a beam focusing optical system closest to the atmospheric pressure chamber is adjacent to the first decompression chamber,
An electron beam processing apparatus provided in a second decompression chamber of a higher vacuum or a third decompression chamber on a higher vacuum side than the second decompression chamber.