JP3376899B2 - Electrical insulation structure in vacuum equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an ion implantation device, a charged particle (ion beam or electron beam) accelerating device, etc., in which a metal plate to which a high voltage is applied is attached to a vacuum container in an annular insulator. The present invention relates to an electrical insulating structure in which a discharge is less likely to occur between a metal plate sandwiching the insulator and a vacuum container in a vacuum device having a structure attached via.

[0002]

2. Description of the Related Art FIG. 7 shows an example of an ion implantation apparatus which is an example of a vacuum apparatus. This ion implantation apparatus introduces an ion beam 4 extracted from an ion source 2 into a processing chamber 12 through a cylindrical or tubular vacuum container 10 to irradiate a target (for example, a semiconductor substrate) 14 with ions to the target 14. It is configured to make an injection. The inside of the vacuum container 10 and the processing chamber 12 is evacuated to a vacuum (for example, about 10 ⁻⁵ to 10 ⁻⁷ Torr) by a vacuum exhaust device (not shown) in order to prevent loss of the ion beam 4.

The ion source 2 is attached to a metal plate (in this example, a metal flange; the same applies hereinafter) 6, to which a high positive voltage (for example, 10 kV) for extracting the ion beam 4 from a high voltage power source 16 is attached. (Approx. 100 kV) is applied. On the other hand, the vacuum container 10 and the processing chamber 12 connected to the vacuum container 10 are normally grounded for safety reasons.
Therefore, the metal plate 6 and the ion source 2 are attached to the vacuum container 10 via the annular insulator 8, and the ion source 2 and the vacuum container 10 are connected to each other via the insulator 8. Therefore, the inside 8a of the insulator 8 is also in a vacuum atmosphere.
The outside 8b of the insulator 8 is at atmospheric pressure.

Between the two end faces 18 of the insulator 8 and the metal plate 6 and the vacuum container 10 facing the end faces 18, a packing 20 for vacuum sealing is provided, respectively. Each packing 20 has a ring shape and is made of an insulating material. For example, each packing 20 is an O-ring or a square ring made of Viton (a trade name of fluororubber; the same applies hereinafter) or silicone rubber.

[0005]

Since the packing 20 for vacuum sealing is provided between the end face 18 of the above-mentioned insulator 8 and the metal plate 6 and the vacuum container 10, the insulator 8 is strictly viewed. End surface 18 of the metal plate 6 and the vacuum container 1
There is no close contact with 0, as shown in FIG.
As shown in the enlarged view, there are minute gaps 24, respectively. In addition, the packing 20 is usually, as shown in the figure,
It is housed in the groove 22 provided in the metal plate 6 and the vacuum container 10.

When such a high voltage as described above is applied to the metal plate 6, that is, between the metal plate 6 and the vacuum vessel 10 in the state where such a gap 24 exists, the minute gap 24 is applied to the portion. A strong electric field is generated. An example of the simulation result is shown in FIG.

FIG. 9 shows one side of the insulator 8 (metal plate 6).
A side) is simulated, and a ground potential portion 26 having a potential of 0 V is arranged in the central portion of the insulator 8 in the axial direction (the traveling direction of the ion beam 4 in FIG. 7) and is opposed to the opposite end face 18. This is a calculation of an equipotential line 28 between the metal plate 6 and the ground potential portion 26 when a voltage of +50 kV is applied to the metal plate 6 to be charged. The other side of the insulator 8 (vacuum container 10 side) also has the same structure as the metal plate 6 side, so that the same result as in FIG. 9 is obtained. The packing 20 is a square ring here because it simulates a compressed O-ring shape. In this example, the dielectric constants of the insulator 8 and the packing 20 were both 9.0, which was close to the value of ceramics. Since 40 equipotential lines 28 are shown between the metal plate 6 and the ground potential portion 26, the potential difference between the two equipotential lines 28 is 1.2 in this example.
It is 5 kV. The above simulation conditions are the same in the cases of FIGS. 5 and 6 described later.

From FIG. 9, it can be seen that the equipotential lines 28 have a high density in the gap 24 between the end face 18 of the insulator 8 and the metal plate 6, and the electric field in this gap 24 is strong. Specifically, in this example, since 11 equipotential lines 28 are concentrated in the gap 24, a potential difference of about 14 kV is generated in the gap 24. Therefore, the distance of the gap 24 (that is, the insulator 8
If the distance between the end face 18 and the metal plate 6) is set to 0.1 mm, a strong electric field of about 1.4 × 10 ⁸ V / m will be generated in this gap 24. Moreover, looking closely, even within the same gap 24, the end portion 3 on the side opposite to the packing 20
The density of equipotential lines 28 becomes higher near 0,
It can be seen that the electric field is stronger.

Returning to FIG. 8, when a strong electric field is generated in the gap 24 between the insulator 8 and the metal plate 6 and the vacuum container 10 as described above, the gap 24 is formed on the vacuum side of the inside 8a of the insulator 8. Electrons are generated by the field emission from the surface of the metal plate 6 or the vacuum container 10 facing toward, and the electrons are accelerated by a strong electric field and collide with the surface of the insulator 8 to further generate secondary electrons. Finally, due to the secondary emission of secondary electrons, a discharge (flashover) occurs between the metal plate 6 and the vacuum container 10 along the surface of the insulator 8. Also on the atmosphere side of the outer side 8b of the insulator 8, due to the strong electric field of the gap 24, corona discharge occurs between the metal plate 6 and the vacuum container 10 along the surface of the insulator 8 from the vicinity of the gap 24.

When the above-mentioned discharge (flashover or corona discharge) occurs along the surface of the insulator 8 between the metal plate 6 and the vacuum container 10, particularly when it frequently occurs,
Since a large load is applied to the power source (high-voltage power source 16) and the insulator 8 is damaged, a voltage cannot be normally applied between the metal plate 6 and the vacuum container 10, and the device May become unstable or may stop malfunctioning. For example, in the case of the ion implanter shown in FIG. 7, it is difficult to stably extract the ion beam 4 from the ion source 2, and a problem occurs in the processing of the target 14. In addition, if the above discharge occurs frequently,
The failure stoppage time of the ion implantation apparatus becomes long, and the reliability and throughput of the apparatus decrease.

Therefore, the main object of the present invention is to make it difficult for electric discharge to occur between the metal plate sandwiching the above-mentioned insulator and the vacuum container.

[0012]

According to a first electrically insulating structure of the present invention, the packings are arranged close to one end of each end face of the insulator, and the other end of each end face is arranged. Insulator rings having elasticity are provided in the vicinity of the portions, respectively, which are in contact with the respective end faces and the vacuum container and the metal plate which face the respective end faces, and which have elasticity (claim 1).

In a second electrically insulating structure according to the present invention, the packings are arranged near one end of each end face of the insulator, and the packings are provided near the other end of each end face. It is characterized in that elastic conductor rings are provided respectively in contact with the end face and the vacuum container and the metal plate facing the end face, respectively (claim 2).

In a third electrically insulating structure according to the present invention, the packings are arranged in the vicinity of the central portion of each end face of the insulator, and in the vicinity of both end portions of each end face, the respective end faces and the opposing ones are provided. A conductive ring having elasticity and being in contact with the vacuum container and the metal plate, respectively, is provided (Claim 3).

In any of the above electric insulation structures, the insulator ring or the conductor ring provided in addition to the packing reduces the voltage sharing in the gap existing between the end face of the insulator and the metal plate and the vacuum container. Because you can
The electric field in the gap weakens. As a result, electric discharge is less likely to occur between the metal plate sandwiching the insulator and the vacuum container.

[0016]

1 is a sectional view showing an example of an electrical insulating structure according to the present invention. The same or corresponding portions as those of the conventional example in FIG. 8 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below. For the configuration of the ion implantation apparatus, refer to FIG. 7 described above and the description thereof.

In this embodiment, the above-mentioned packings 20 are provided in the vicinity of one end of each end face 18 of the insulator 8.
That is, in this example, the end faces 18 and the metal plate 6 facing the end faces 18 are arranged near the other end of each end face 18, that is, near the end closer to the outer side 8b. Insulating rings 34 having elasticity are provided in contact with the vacuum container 10 respectively. In this example, each insulator ring 34 is housed in the groove 32 provided in the metal plate 6 and the vacuum container 10, respectively.

Each insulator ring 34 is an O-ring or a square ring made of, for example, Viton or silicone rubber. However, other materials and cross-sectional shapes may be used.

FIG. 5 shows an example of the simulation result of the electric field distribution in the structure corresponding to the electric insulation structure of FIG. As described above, the simulation conditions in FIG. 5 (and FIG. 6 described later) are the same as those in FIG. As for the insulator ring 34, similar to the case of the packing 20, a simulation was performed with a relative dielectric constant of 9.0 and a square ring shape.

From FIG. 5, the density of equipotential lines 28 in the gap 24 between the end face 18 of the insulator 8 and the metal plate 6 is considerably lower than that in the conventional example shown in FIG. It can be seen that the electric field in this gap 24 is weakened (relaxed). Specifically, in this example, even if there are many gaps 24, there are only seven equipotential lines 28, so the potential difference in this gap 24 is approximately 9 kV, and
If the distance of 4 is set to 0.1 mm as in the conventional example,
The electric field in the gap 24 is weakened to about 9 × 10 ⁷ V / m.

Moreover, in the conventional example shown in FIG. 9, the electric field is particularly strong in the vicinity of the end portion 30 on the opposite side of the packing 20 as described above, whereas in this embodiment, the end surface of the insulator 8 is formed. Since the packing 20 and the insulator ring 34 are distributed in a well-balanced manner near the inner end and the outer end of the 18, the generation of a region where the electric field is particularly strong can be prevented. .

The side of the insulator 8 opposite to the one shown in FIG.
Since the side) also has the same structure as the metal plate 6 side,
Similar results are obtained. The same applies to other embodiments described later.

In this way, the electric field in the gap 24 between the end face 18 of the insulator 8 and the metal plate 6 and the vacuum container 10 is weakened, so that the metal plate 6 sandwiching the insulator 8 and the vacuum container 10 are sandwiched. The flashover and corona discharge due to the field emission described above are less likely to occur. Therefore, it is possible to improve the reliability of the vacuum device such as the ion implantation device which adopts such an electric insulation structure and reduce the failure stop time due to the discharge.

It should be noted that since the vacuum sealing between the insulator 8 and the metal plate 6 and the vacuum container 10 is performed by the packing 20, it is not necessary to give the insulating ring 34 a vacuum sealing function, but it is necessary. May be. The same applies to the conductor ring 36 described later.

Further, the packing 20 and the insulator ring 34 are turned inside out, that is, the packing 20 is placed outside the insulator 8b.
The insulator ring 34 may be provided closer to the inner side 8a, but if the insulator ring 34 does not have a vacuum sealing function, outgas to the vacuum side (release gas)
From the viewpoint of minimizing the number of cases, it is preferable to provide the packing 20 closer to the inner side 8a as in this example. The same applies to the relationship between the conductor ring 36 and the packing 20 described later.

Next, another embodiment will be described focusing on the differences from the embodiment of FIG.

In the embodiment of FIG. 2, a conductor ring 36 is provided instead of the insulator ring 34 of the embodiment of FIG. That is, at the same position as that of the insulator ring 34 of the embodiment of FIG. 1, that is, near each end face 18 of the insulator 8 near the outside 8b, each end face 18 and the metal plate 6 and the vacuum container facing it. 10 and 10 are respectively provided with elastic conductor rings 36. Each conductor ring 3
Also in this example, 6 are housed in the grooves 32 provided in the metal plate 6 and the vacuum container 10, respectively.

Each conductor ring 36 is made of metal O, for example.
A ring (that is, a metal O-ring), a ring-shaped packing made of conductive rubber (for example, an O-ring or a square ring), and a conductor (for example, beryllium copper) are wound in a thin coil shape to form a ring shape.

FIG. 6 shows an example of the simulation result of the electric field distribution in the structure corresponding to the electrically insulating structure of FIG. Similar to the case of the packing 20, the conductor ring 36 has a square ring shape in this example for simulation.

From FIG. 6, the density of equipotential lines 28 in the gap 24 between the end face 18 of the insulator 8 and the metal plate 6 is much lower than in the case of the conventional example shown in FIG. It can be seen that the electric field in this gap 24 is weakened. Specifically, in this example, even if many gaps 24 are seen,
Since there are only equipotential lines 28 of the book, the potential difference in the gap 24 is about 5 kV. If the distance of the gap 24 is, for example, 0.1 mm as described above, the electric field in the gap 24 is about 5 × 10. Weakened to ⁶ V / m. That is, it is two orders of magnitude lower than in the conventional example.

As a result, also in the case of this embodiment, the above-mentioned discharge is unlikely to occur between the metal plate 6 sandwiching the insulator 8 and the vacuum container 10.

The insulator ring 34 and the conductor ring 3
As in the embodiment shown in FIG. 3, 6 may be provided at a corner portion of each end face 18 of the insulator 8 toward the outside 8b (atmosphere side),
Also in this case, it can be easily understood with reference to FIGS. 5 and 6 that an electric field distribution substantially similar to that in FIGS. 5 and 6 is obtained, that is, the electric field in the gap 24 is weakened.

In the embodiment of FIG. 4, the packing 20 described above is used.
Is arranged near the center of each end surface 18 of the insulator 8, and the conductor rings 36 similar to those in the embodiment of FIG. The elastic conductive rings 36 are provided so as to be in contact with the metal plate 6 and the vacuum container 10, respectively. Also in this example, each conductor ring 36 is housed in the groove 32 provided in the metal plate 6 and the vacuum container 10, respectively.
The material and the like of each conductor ring 36 are as described above.

It can be easily understood that the electric field in each gap 24 is weakened also in the embodiment of FIG. 4 by referring to FIG.

In the embodiment of FIG. 4, the packing 2
The positions of 0 and the conductor ring 36 may be exchanged, that is, the conductor ring 36 may be provided near the center of each end face 18 and the packings 20 may be provided near both ends thereof. Although it becomes stronger, the same effect as in the case of the embodiment of FIG. 4 can be obtained.

The electrical insulation structure as described above is shown in FIG.
A vacuum device other than the ion implantation device shown in, for example, a charged particle source (that is, an ion source, an electron beam source, etc.) to which a high positive or negative voltage is applied is attached to a metal flange, and the metal flange is attached to an annular insulator. It can also be applied to a vacuum device having a structure attached to a vacuum container via

[0037]

As described above, according to the present invention, the voltage sharing in the gap existing between the end face of the insulator and the metal plate and the vacuum container is achieved by the insulator ring and the conductor ring provided in addition to the packing. Can be alleviated, the electric field in the gap is weakened. As a result, electric discharge is less likely to occur between the metal plate sandwiching the insulator and the vacuum container. Therefore,
It is possible to improve the reliability of the vacuum device that employs such an electrical insulation structure and reduce the failure stop time due to discharge.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an electrically insulating structure according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the electrically insulating structure according to the present invention.

FIG. 3 is a cross-sectional view showing another example of the electrically insulating structure according to the present invention.

FIG. 4 is a cross-sectional view showing another example of the electrically insulating structure according to the present invention.

5 is a diagram showing an example of a simulation result of an electric field distribution in a structure corresponding to the electrically insulating structure of FIG.

6 is a diagram showing an example of a simulation result of an electric field distribution in a structure corresponding to the electrically insulating structure of FIG.

FIG. 7 is a schematic cross-sectional view showing an example of an ion implantation apparatus which is an example of a vacuum apparatus.

FIG. 8 is an enlarged cross-sectional view around an insulator in FIG.

9 is a diagram showing an example of a simulation result of an electric field distribution in a structure corresponding to the structure of FIG.

[Explanation of symbols]

2 Ion source 6 metal plate 8 Insulator 10 vacuum container 18 end face 20 packing 24 gaps 34 Insulator ring 36 conductor ring

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Claims (3)

(57) [Claims] 1. A vacuum vessel, to which a metal plate to which a high voltage is applied is attached via an annular insulator, and a ring shape is provided between two end faces of the insulator and the vacuum vessel and the metal plate facing the two end faces. In a vacuum device provided with packings for vacuum seals each made of an insulating material, the packings are arranged close to one end of each end face of the insulator, and the other end of each end face is arranged near the end face. An electrically insulating structure in a vacuum device, wherein each of the end faces is provided with an elastic insulator ring which is in contact with the vacuum container and the metal plate facing the end face. 2. A metal plate to which a high voltage is applied is attached to a vacuum container via an annular insulator, and a ring shape is formed between the two end faces of the insulator and the vacuum container and the metal plate facing the two end faces. In a vacuum device provided with packings for vacuum seals each made of an insulating material, the packings are arranged close to one end of each end face of the insulator, and the other end of each end face is arranged near the end face. An electrically insulating structure in a vacuum device, wherein each of the end faces is provided with an elastic conductor ring in contact with the vacuum container and the metal plate facing the end face. 3. A metal plate to which a high voltage is applied is attached to a vacuum container via an annular insulator, and a ring shape is provided between two end faces of the insulator and the vacuum container and the metal plate facing the two end faces. In a vacuum device provided with packings for vacuum seals each made of an insulating material, each packing is arranged near the center of each end face of the insulator, and in the vicinity of both end parts of each end face, each end face is An electrically insulating structure in a vacuum device, characterized in that conductive rings having elasticity are respectively provided in contact with the vacuum container and the metal plate facing each other.