JP2004030997A - Electron gun for electron beam machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an electron gun for electron beam machining preventing wear/break of a filament due to ion flow generated by an electron beam and unstable output voltage from a high-voltage power source and requiring no consumable part for coping with the ion flow. <P>SOLUTION: A deflection part 13 deflecting the electron beam EB is arranged in a beam formation electrode 12 accelerating an electron emitted from the filament 11 and forming an electric field generating the electron beam EB so that the electron beam EB is protruded on the emission side beyond an opening part. A grounded anode 15 forming the electric field generating the electron beam EB with the beam formation electrode 12 is arranged face to face to the deflection part 13 while putting the electron beam EB between them. In the progress direction of the main flow of ions ionized from the electron beam, a grounded ground metal plate 16 is arranged. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron gun for electron beam processing used in electron beam processing such as vapor deposition and melting. Specifically, it is possible to prevent the filament from being worn out or broken by the ion current generated by injecting the electron beam in the vacuum chamber, to prevent the output voltage of the high voltage power supply from becoming unstable, and to cope with the ion current. The purpose of the present invention is to provide an electron gun for electron beam processing that does not require consumables for use.
[0002]
[Prior art]
The configuration of a conventionally used electron beam processing electron gun will be described with reference to FIG. 6 (conventional example 1). Here, FIG. 6 is a cross-sectional view schematically showing the configuration of the first conventional example. Hereinafter, a case where the present invention is used for a vapor deposition apparatus will be described as an example.
[0003]
In FIG. 6, reference numeral 61 denotes a filament which is heated by the flow of an electric current and emits thermoelectrons. The filament 61 is disposed inside a cylindrical beam forming electrode 62 having a circular opening 63 for emitting thermions emitted therefrom. A flat plate-shaped anode 64 provided with a hole 65 slightly larger than the opening 63 of the beam forming electrode 62 is disposed so as to face the beam forming electrode 62.
[0004]
A negative high voltage is applied to the beam forming electrode 62 here, and the anode 64 is grounded and kept at the ground potential, or a positive voltage is applied. As a result, an electric field for accelerating the thermoelectrons emitted from the filament 61 and generating an electron beam is formed.
[0005]
The electron gun composed of the above-described components is disposed in a sealed vacuum chamber (not shown). A reactive gas such as an inert gas or oxygen may be introduced.
[0006]
Therefore, when the electron gun configured as described above is operated, the electron beam EB emitted from the electron gun is deflected by a magnetic field to rotate, for example, 270 degrees, as shown by a broken line, and is arranged at a predetermined position. Irradiation is performed on the vapor deposition material accommodated in the set hearth. As a result, the vapor deposition material is heated and sublimated by the energy of the electron beam EB, and the generated vapor deposition particles rise toward the material to be deposited disposed above the hearth, and adhere to the material to form a thin film. Will be.
[0007]
However, when the electron beam EB is emitted from the electron gun, the positive ions of the atmospheric gas ionized by the electron beam EB are attracted to the negative potential of the beam forming electrode 62. That is, the ion flow I flows toward the filament 61 in such a manner as to flow backward to the flow of the electron beam EB.
[0008]
When the shapes of the beam forming electrode 62 and the anode 64 are respectively symmetrical, the ion current I converges and collides with the filament 61 through the hole 65 of the anode 64 and the opening 63 of the beam forming electrode 62. When the ion flow I collides with the filament 61, the ion sputtering causes the filament 61 to be worn and further to be disconnected.
[0009]
If the filament 61 is worn out and disconnected, the injection of the electron beam EB stops, and the vapor deposition operation is interrupted. Further, when the ion current I collides with a member receiving a high voltage from a high voltage power supply that outputs a negative high voltage applied to the beam forming electrode 62 and other members, a discharge due to ions is generated. The output voltage from the power supply becomes unstable.
[0010]
Therefore, in another conventional example, the following configuration is used, and its outline is shown in FIG. 7 and described (refer to Conventional Example 2: United States Patent Number 6,064,686).
[0011]
In FIG. 7 (cross-sectional view), the beam forming electrode 72 arranged so as to surround the filament 71 is formed in a cylindrical shape. One of the portions sandwiching the opening 74 for emitting thermoelectrons from the filament 71 is constituted by a bent portion 73 formed in a rectangular shape in cross section. Similarly, in the anode 75, one of the portions sandwiching the hole 78 is formed by a bent portion 76 having an S-shaped cross section.
[0012]
A hole 77 is formed in the bent portion 76 of the anode 75, and an ion target 100 using a high melting point metal such as molybdenum and collided with the ion stream I through the hole 77 is used as the anode 75. Is attached to the bent portion 73 of the beam forming electrode 72 so as not to be in contact with the bent portion 76.
[0013]
Therefore, when the electron gun configured as described above is operated, the electric field formed by the beam forming electrode 72 and the anode 75 is symmetric, but the ions have a larger mass than the electrons and the flow is bent. Due to the difficulty, the ion flow I does not collide with the filament 71 but with the ion target 100.
[0014]
As described above, in the second conventional example, although the electric field formed by the beam forming electrode 72 and the anode 75 is symmetric, the ion flow I does not collide with the filament 71.
[0015]
[Problems to be solved by the invention]
According to the first conventional example shown in FIG. 6, as described above, the ion flow I collides with the filament 61, so that the filament 61 is worn and disconnected. As a result, there is a problem to be solved that the injection of the electron beam EB is stopped and the vapor deposition operation is interrupted.
[0016]
Further, since the ion current I collides with a member receiving a high voltage from a high voltage power supply that outputs a negative high voltage applied to the beam forming electrode 62 and discharge occurs, the negative high voltage is unstable. There was also an unsolved problem that it would be.
[0017]
On the other hand, according to the conventional example 2 shown in FIG. 7, since the ion current I does not collide with the filament 71, it is possible to prevent the filament 71 from being worn out or broken, and therefore, the electron beam EB of the electron beam EB is prevented. There is no problem that the vapor deposition operation is interrupted by stopping the injection.
[0018]
However, since a complicated configuration is used in which the bent portions 73 and 76 are provided in each of the beam forming electrode 72 and the anode 75, there is a problem that the cost is increased. Further, even though the wear and breakage of the filament 71 due to ion sputtering can be avoided, the ion target 100 attached to the bent portion 73 of the beam forming electrode 72 to which a negative high voltage is applied is accelerated. As the ions collide, the ion target 100 is worn by the energy. If the ion target 100 becomes worn and can no longer be used, a new ion target 100 must be remounted. In other words, this becomes a factor of the running cost of the apparatus, and involves the inconvenience that the ion target 100 must be remounted each time.
[0019]
As described above, according to the conventional example 2 shown in FIG. 7, it is possible to solve the problem that the wear and disconnection of the filament 71 can be avoided, but the production cost and the running cost of the apparatus increase. There were issues to be addressed.
[0020]
[Means for Solving the Problems]
Therefore, the present invention has been made to solve the above problems. Therefore, in the present invention, a configuration for forming an electric field for generating an electron beam by accelerating the thermoelectrons emitted from the filament is asymmetric, that is, a deflection unit for deflecting the electron beam is provided with an electron rather than an opening. It is provided on the beam forming electrode so as to protrude to the side where the beam is emitted. An anode, which is maintained at ground potential or positive potential, forms an electric field for generating an electron beam with the beam forming electrode. Then, a member made of a grounded conductor is arranged in the traveling direction of the main flow of ions ionized by the electron beam. The above means are used.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention is shown and described in FIG. Here, FIG. 1 is a sectional view schematically showing a configuration of an electron gun for electron beam processing according to the present invention.
[0022]
In FIG. 1, reference numeral 10 denotes an electron beam emitting unit that emits an electron beam EB. The electron beam emitting section 10 has a rectangular tube-shaped beam forming electrode 12 for forming an electric field for accelerating thermoelectrons emitted from the filament 11 and generating an electron beam EB, and has an L-shaped cross section. A plate-shaped anode 15 is disposed.
[0023]
A negative high voltage is applied to the former beam forming electrode 12, and its shape is formed asymmetrically with respect to a plane A along a cross-sectional direction indicated by a two-dot chain line as shown in FIG. 2 (perspective view). I have. That is, the lower part of the beam forming electrode 12 protrudes forward (on the side where the electron beam EB is emitted) from the opening 14, and this protruding portion serves as a deflection portion for deflecting the emitted electron beam EB. 13.
[0024]
On the other hand, as shown in FIG. 1, the anode 15 is grounded and kept at the ground potential, and the upper end of the anode 15 is positioned above the beam forming electrode 12 so that the front edge thereof faces the deflection portion 13 of the beam forming electrode 12. Are arranged at predetermined intervals.
[0025]
Thus, in the electron gun according to the present invention, the shape of the beam forming electrode 12 is formed asymmetrically. Therefore, the electric field formed by the beam forming electrode 12 and the anode 15 to generate the electron beam by accelerating the thermoelectrons emitted from the filament 11 is asymmetric. As a result, as shown in the figure, the ion flow I does not collide with the filament 11 and flows in a different direction.
[0026]
In the conventional example 2 of FIG. 7, the ion flow I flowing while changing the direction uses a configuration in which the ion flow I collides with the ion target 100. However, the electron gun according to the present invention employs a configuration in which the ion target 100 is not used, and the grounded metal plate 16 is provided, thereby receiving the ion current I. As a result, the ions are decelerated, and their main flow reaches the ground metal plate 16 and contacts the ground metal plate 16 without flowing through the metal, and flows to the ground. Therefore, the ground metal plate 16 is not worn by ion sputtering.
[0027]
Here, in FIG. 1, illustration of a configuration for supporting the electron beam emitting unit 10 is omitted, and details of the configuration are shown in FIG.
[0028]
In FIG. 3A (perspective view), the electron beam emitting unit 10 is supported by two columnar columns 21a and 21b, and each column 21a and 21b is formed by a plate-shaped high voltage power supply member 22a and 22b. Supported. Each of the high-voltage power supply members 22a and 22b is supported by each of insulators 23a to 23 using ceramics or the like, which is erected on the base 24.
[0029]
That is, the electron beam emitting section 10 is supported so as to be bridged between the high voltage power supply members 22a and 22b, and the electron beam emitting section 10 is formed so that a gap is formed between the electron beam emitting section 10 and the base 24. The injection unit 10 is provided. The ion flow I flows through the gap and reaches the ground metal plate 16.
[0030]
As described above, since the support of the electron beam emitting unit 10 may be configured so as not to hinder the path of the ion current I, for example, as shown in FIG. The electron beam emitting unit 10 may be supported by the high voltage power supply members 31a and 31b.
[0031]
Although FIG. 1 shows a configuration in which the anode 15 is grounded and kept at the ground potential, a positive voltage may be applied to the anode 15. Further, a metal plate having an L-shaped cross section is shown as a member for receiving the ion flow I. However, the present invention is not limited to this, and any shape may be used as long as the member is made of a conductor.
[0032]
The beam forming electrode 12 is not limited to the shape shown in FIG. 2 as long as the beam forming electrode 12 has an asymmetric shape, that is, a shape in which the deflection portion 13 projects from the opening portion 14 (FIG. 2) to the side where the electron beam EB is emitted. Absent. According to the shape of the filament 11 used, for example, as shown in FIG. 4A (perspective view), the cross-sectional shape along the line AA is changed into an L shape like the beam forming electrode 12 in FIG. The opening 14B of the beam forming electrode 12B may be formed in a flat shape without being formed.
[0033]
Alternatively, as shown in FIG. 4B (perspective view), the beam forming electrode 12C may be formed as a flat plate having an L-shaped cross section instead of a cylindrical shape. In this case, the anode 15B is not formed in an L-shaped cross section as in the case of the anode 15 of FIG. May be arranged.
[0034]
Further, the anode 15 is not limited to the shape shown in FIG. In addition to the shape shown in FIG. 4B, for example, as shown in FIG. 5 (cross-sectional view), a flat plate-like anode 17 similar to the anode 64 in the conventional example 1 of FIG. The deflection portion 13 of the beam forming electrode 12 indicated by a broken line may be located in the hole 18 provided. In that case, the portion of the anode 17 on the side facing the deflection portion 13 with the electron beam EB interposed therebetween has an action of forming an electric field for generating the electron beam EB, and is substantially shown in FIG. The same operation and effect as those of the anode 15 can be obtained.
[0035]
【The invention's effect】
As is apparent from the above description, according to the present invention, the configuration for forming an electric field for generating an electron beam by accelerating the thermoelectrons emitted from the filament is made asymmetric, so that the electron beam The ionized ions do not collide with the filament. Therefore, it is possible to prevent the filament from being worn or broken due to ion sputtering.
[0036]
As a result, the life of the filament to be used can be extended, and in the case of a vapor deposition device, the interruption of the vapor deposition operation due to the stop of the injection of the electron beam can be avoided. That is, the workability of the vapor deposition process is improved, and the vapor deposition cost is reduced.
[0037]
Also, since the ion current does not collide with the member receiving the high voltage from the high voltage power supply that outputs a negative high voltage, no discharge due to ions occurs, and the stable flow from the high voltage power supply does not occur. High voltage supply can be realized.
[0038]
Furthermore, there is no need to use consumables for dealing with ion sputtering, such as the ion target in Conventional Example 2. The running cost of the apparatus can be reduced.
[0039]
Moreover, the above effect can be obtained with a simple configuration, that is, at low cost. Therefore, the effect of the present invention in the electron beam processing electron gun is extremely large in practical use.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of the present invention.
FIG. 2 is a perspective view showing a shape of a beam forming electrode shown in FIG.
FIG. 3 is a perspective view showing a configuration for supporting the electron beam emitting unit shown in FIG.
FIG. 4 is a perspective view showing another example of the shape of the beam forming electrode constituting the electron beam emitting unit shown in FIG.
5 is a sectional view showing another example of the shape of the anode constituting the electron beam emitting section shown in FIG.
FIG. 6 is a cross-sectional view showing the configuration of Conventional Example 1.
FIG. 7 is a cross-sectional view showing the configuration of Conventional Example 2.
[Explanation of symbols]
Reference Signs List 10 Electron beam emitting part 11 Filament 12, 12B, 12C Beam forming electrode 13 Deflection part 14, 14B Opening 15, 15B Anode 16 Ground metal plate 17 Anode 18 Hole 21a, 21b Column 22a, 22b High voltage power supply member 23a- 23d insulator 24 bases 31a, 31b high voltage power supply member 61 filament 62 beam forming electrode 63 opening 64 anode 65 hole 71 filament 72 beam forming electrode 73 bent portion 74 opening 75 anode 76 bent portion 77 hole 78 hole 100 ion・ Target EB Electron beam I Ion flow

Claims (1)

A filament (11) that emits thermoelectrons when heated by flowing an electric current;
The thermoelectrons emitted from the filament are accelerated by a deflection section (13) for deflecting an electron beam (EB) provided to protrude from the openings (14, 14B). Beam forming electrodes (12, 12B, 12C) to which a negative high voltage is applied for forming an electric field for generating a beam;
An anode (15, 17) maintained at one of a ground potential and a positive potential for forming an electric field for generating the electron beam with the beam forming electrode;
An electron gun for processing an electron beam, comprising: a member (16) made of a grounded conductor, which is arranged in the direction of travel of the main flow of ions ionized by the electron beam.

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