JP2001021700A - Electron beam irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the uniformity of electron dose distribution from worsening by the warping of a filament assembly by the heat from a filament. SOLUTION: Near the middle of a filament assembly 8 in Y-direction having a filament 10 is fixed onto a shield electrode 4. Both ends of the filament assembly 8 in Y-direction are fixed to the shield electrode 4 by a fixing means 32 allowing extension of the both ends in Y-direction and disturbing the motion in up and down directions. The fixing means 32 is constituted of a connection plate 34 having a long hole 36, male screws 38 having a column part 42 of length C which is a little longer than the plate thickness B, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure in which a filament assembly (filament assembly) is mounted in a shield electrode. The present invention relates to an electron beam irradiation apparatus for performing a process, and more particularly, to a means for preventing the filament assembly from warping due to heat from the filament and deteriorating the uniformity of the electron dose distribution.

[0002]

2. Description of the Related Art FIG.
1 shows an example of an electron beam irradiation apparatus as described in Japanese Patent Application Publication No. 0-205. This electron beam irradiation apparatus is called a non-scan type (or area type) which does not scan the electron beam 22,
It includes a cylindrical vacuum vessel 2 that is long in a certain direction (Y direction in this specification), a shield electrode 4 housed in the vacuum vessel 2, a filament assembly 8 mounted in the shield electrode 4, and the like. ing.

[0003] The shield electrode 4 has a round cross section (for example, a semicircular shape, a semielliptical shape, etc.) and a cylindrical shape long in the Y direction, and has a rectangular opening 6 long in the Y direction on the lower surface thereof. are doing. The shield electrode 4 acts to reduce the concentration of the electric field due to the acceleration voltage applied between the vacuum vessel 2 and the filament assembly 8.

In this example, the filament assembly 8 has a structure in which a plurality of linear (or rod-shaped) filaments 10 are supported in a space between two right and left supporters 16 having a U-shaped cross section in the Y direction. ing. The planar shape of the filament assembly 8 is a rectangle that is long in the Y direction.

[0005] There are various support structures for each filament 10, but in this example, as an example, 2
The structure is such that the filament 10 is supported between the support plates 12. The insulating base 14 is mounted on the support 16. A filament support structure as described in JP-A-11-133197 may be used.

Further, in this example, the extraction electrode 20 supported by the frame 18 is attached to the lower portion of the filament assembly 8. The extraction electrode 20 has, for example, a structure in which mesh, rod, or linear electrodes are combined in a blind or grid shape.

Conventionally, the filament assembly 8 has a lower frame 18 fitted into the opening 6 of the shield electrode 4 from above, and two fixing screws 30 near the center of the filament assembly 8 in the Y direction. It is attached to the shield electrode 4 by being fixed to the lower surface of the shield electrode 4 by (see also FIG. 4). Thus, the shield electrode 4, the filament assembly 8, and the extraction electrode 20 are set to the same potential.

Electrons emitted from each filament 10 are passed through an extraction electrode 20 by an electron beam 22 by an acceleration voltage applied between the shield electrode 4 and the like and the vacuum vessel 2.
As it is accelerated and pulled out. The electron beam 22 is provided at the opening of the vacuum vessel 2, passes through an irradiation window 24 having a window foil 26 for separating the atmosphere inside and outside the vacuum vessel, is drawn out of the vacuum vessel 2, Irradiated at 28 and is subjected to processing such as reforming.

[0009]

In the above-described electron beam irradiation apparatus, the filament assembly 8 is merely fixed to the shield electrode 4 by the two fixing screws 30 near the center in the Y direction as described above. When the temperature of the support 16 increases due to the heat from the filaments 10, both ends of the filament assembly 8 separate from the shield electrode 4 and warp as shown in FIG. 4, for example. For example, the length of the filament assembly 8 in the Y direction is about 2
In the case of m, the amount A of warpage at both ends of the filament assembly 8 may be as large as about 15 mm.

In this case, since the electron beam 22 drawn from the warped portion of the filament assembly 8 spreads outward, the dose near the both ends of the electron beam 22 in the Y direction decreases, and the electron dose distribution in the Y direction becomes uniform. The sex worsens. As a result, the uniformity of the treatment of the irradiation object 28 using such an electron beam 22 also deteriorates.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent the uniformity of the electron dose distribution from being deteriorated due to the warpage of the filament assembly caused by the heat from the filament.

[0012]

According to the present invention, there is provided an electron beam irradiating apparatus, wherein a portion near the center of the filament assembly in the Y direction is fixed to the shield electrode, and both ends of the filament assembly in the Y direction are connected to the both ends. The portion is fixed to the shield electrode by fixing means for allowing expansion and contraction of the portion in the Y direction and preventing movement in the vertical direction.

According to the above construction, not only the vicinity of the center of the filament assembly is fixed, but also both ends in the Y direction are fixed to the shield electrode by the fixing means for preventing the vertical movement thereof. It is possible to prevent the filament assembly from warping due to heat from the filament.

In addition, since the fixing means allows both ends of the filament assembly to expand and contract in the Y direction, the filament assembly is moved by the heat from the filament.
Even if thermal expansion occurs in the direction, it can escape without restraining it. Therefore, it is possible to prevent the filament assembly from waving in the Y direction.

As a result, even if the temperature of the filament assembly rises due to the heat from the filament, the deformation of the filament assembly can be prevented, so that the uniformity of the electron dose distribution can be prevented from deteriorating.

[0016]

FIG. 1 is a schematic side view showing an example of the periphery of a shield electrode of an electron beam irradiation apparatus according to the present invention. FIG. 2 is an enlarged and exploded perspective view showing an example of the vicinity of an end of the shield electrode and the filament assembly in FIG. Parts that are the same as or correspond to those of the conventional example shown in FIG. 3 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below. The configuration of the entire electron beam irradiation apparatus is, for example, the same as that shown in FIG.

In this electron beam irradiation apparatus, the vicinity of the center of the filament assembly 8 in the Y direction is fixed to the shield electrode 4 by two fixing screws 30.
This is the same as the conventional example.

Further, both ends of the filament assembly 8 in the Y direction are fixed to the shield electrode 4 by fixing means 32 which permits expansion and contraction of the both ends in the Y direction and prevents movement in the vertical direction.

A specific example of the fixing means 32 will be described with reference to FIG. However, in FIG.
The illustration of the support structure of 0, the extraction electrode 20, and the like are omitted.

The two right and left supports 16 are connected to each other by connecting plates 34 at both ends in the Y direction. However, the means for fixing the connecting plate 34 to each support 16 may be a known means (for example, a screw), and is not shown here. The support 16 and the connecting plate 34 form a three-dimensional frame-like structure as a whole.

In this example, two long holes (elliptical holes) 36 are formed in the connecting plate 34 in the Y direction, and two male screws 38 are passed through each of the long holes 36, respectively. Two female screw portions 46 provided at corresponding positions of the lower shield electrode 4 are screwed respectively. Female thread 46
May be provided with a reinforcing plate or the like that increases the thickness as necessary.

Each male screw 38 has a head 40 and a screw 4
4 and has an unthreaded cylindrical portion 42. The short diameter D of the long hole 36 is, of course, slightly larger than the outer diameter of the cylindrical portion 42. The screw portion 44 and the female screw portion 46 are screwed. However, since the diameter of the cylindrical portion 42 is larger than the diameter of the screw portion 44 and the female screw portion 46 screwed thereto, when the lower end surface of the cylindrical portion 42 contacts the upper end surface of the female screw portion 46, the male screw 38 is further increased. Can not be screwed.
In addition, the length C of the cylindrical portion 42 is
Is slightly larger than the thickness B of the portion. For example,
C−B is about 0.5 mm.

Therefore, even if the male screw 38 is tightened, a play corresponding to the distance CB occurs between the lower surface of the head 40 and the upper surface of the connecting plate 34. Moreover, the hole of the connecting plate 34 is a long hole 36. Therefore, the movement of the connecting plate 34 in the Y direction,
That is, expansion and contraction of the filament assembly 8 in the Y direction can be allowed. In addition, the vertical movement of the connecting plate 34, that is, the rising of the filament assembly 8,
-B or less.

The connecting plate 3 having the long hole 36 as described above.
In this example, the fixing means 32 is constituted by a male screw 38 having a cylindrical portion 42 and a female screw portion 46 provided on the shield electrode 4.

According to the above configuration, not only the vicinity of the center of the filament assembly 8 is fixed to the shield electrode 4 by the fixing screw 30, but also the both ends in the Y direction of the filament assembly 8 are prevented from moving in the vertical direction. Since the filament assembly 8 is fixed to the shield electrode 4 by the fixing means 32, it is possible to prevent the filament assembly 8 from warping due to heat from the filament 10.
That is, in this example, the warpage is equal to the above-mentioned CB ≒ 0.
It can be limited to 5 mm or less. If CB is made smaller, it can be further reduced. That is, the warpage can be reduced to almost zero.

Furthermore, since the fixing means 32 allows the ends of the filament assembly 8 to expand and contract in the Y direction, even if the filament assembly 8 thermally expands in the Y direction due to the heat from the filament 10, it is restrained. You can escape without it. Therefore, it is possible to prevent the filament assembly 8 from being deformed in the Y direction.

As a result, even if the temperature of the filament assembly 8 rises due to the heat from the filament 10, the deformation of the filament assembly 8 can be prevented, so that the uniformity of the dose distribution of the electron beam 22 in the Y direction is reduced. Can be prevented. That is, the electron beam 22 with high uniformity of the dose distribution can be extracted. Therefore, the uniformity of the processing for the irradiation object 28 (see FIG. 3) is also improved.

Although it is preferable that each support 16 constituting the filament assembly 8 has a U-shaped cross section as in this example, since the strength can be easily improved, other shapes such as an L-shaped cross section are preferable. Shape or a simple plate shape.

In place of the two supports 16 and the two connecting plates 34, for example, two frames arranged vertically and a support which supports the two frames at an interval are used. It may be constituted by.

The frame 18 and the extraction electrode 20
May be fixed to the opening 6 of the shield electrode 4 instead of the lower surface of the filament assembly 8 as in this example.

[0031]

As described above, according to the present invention, not only is the vicinity of the center of the filament assembly fixed,
Since both ends in the Y direction are also fixed to the shield electrode by fixing means for preventing the movement in the vertical direction, it is possible to prevent the filament assembly from warping due to heat from the filament. In addition, since the fixing means allows both ends of the filament assembly to expand and contract in the Y direction, it is possible to prevent the filament assembly from waving in the Y direction. As a result, even if the temperature of the filament assembly rises due to the heat from the filament, the deformation of the filament assembly can be prevented, so that the uniformity of the electron dose distribution can be prevented from deteriorating.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example around a shield electrode of an electron beam irradiation apparatus according to the present invention.

2 is an enlarged and exploded perspective view showing an example of the vicinity of an end of a shield electrode and a filament assembly in FIG. 1;

FIG. 3 is a sectional view showing an example of an electron beam irradiation device.

FIG. 4 is a schematic side view showing an example around a shield electrode of a conventional electron beam irradiation apparatus.

[Explanation of symbols]

 Reference Signs List 4 shield electrode 6 opening 8 filament assembly 10 filament 16 support 20 extraction electrode 22 electron beam 30 fixing screw 32 fixing means 34 connecting plate 38 male screw 46 female screw

Claims (1)

[Claims] 1. A shield electrode having a round section and a cylindrical shape elongated in the Y direction and having a rectangular opening on the lower surface thereof elongated in the Y direction, and a plurality of wires in a space between the left and right supports. And a rectangular filament assembly having a planar shape elongated in the Y direction and supporting the filaments arranged in the Y direction, and the filament assembly is inserted into the shield electrode and attached to the opening thereof. In the irradiation device, the vicinity of the center of the filament assembly in the Y direction is fixed to the shield electrode, and both ends of the filament assembly in the Y direction are allowed to expand and contract in the Y direction and are vertically moved. An electron beam irradiating device fixed to the shield electrode by fixing means for preventing the electron beam irradiation.