JPH0719083Y2 - Ion source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an ion source used in, for example, an ion implantation apparatus, and more specifically, a means for preventing flashover in a portion of its extraction electrode system. Regarding

[Conventional technology]

FIG. 2 is a schematic diagram showing a basic configuration example of an ion source.

This ion source is a plasma source unit 2 that produces a plasma 8.
And an extraction electrode system 10 for extracting the ion beam 16 from the plasma source portion 2 (more specifically, the plasma 8 there) by the action of an electric field.

In this example, the plasma source unit 2 has a plasma generation container 4 and a filament 6 into which an ionized substance such as gas is introduced, and a plasma 8 is generated by arc discharge between the two.

In this example, the extraction electrode system 10 is a porous electrode, and is a positive electrode 12 that is set to a positive potential, a negative electrode 13 that is on the downstream side and is set to a negative potential, and that is on the downstream side. It is composed of a ground electrode 14 which is set to the ground potential.

FIG. 3 is an enlarged sectional view partially showing a conventional example of a specific structure around the extraction electrode system 10 of the ion source of FIG.

A high-voltage flange 20 to which a positive high voltage is applied and a ground flange to be grounded at both ends of the cylindrical insulating spacer 22.
24 are provided respectively.

The positive electrode 12 is attached to this high-pressure flange 20, and a positive high voltage is applied via this high-pressure flange 20.

The ground electrode 14 is supported from the ground flange 24 by a cylindrical metal support frame 32, and is set to the ground potential via these.

The negative electrode 13 is supported by the support frame 32 via an insulator (not shown), for example. In addition, the ground flange 24 is passed through the current introducing terminal 26 having an insulating tube 26a and a conductor 26b, and (and more specifically, the conductor 26b
And) the negative electrode 13 is connected by a connecting line 28. 30
Is a terminal. With such a structure, a negative voltage is externally applied to the negative electrode 13.

[Problems to be solved by the device]

In the ion source as described above, a high voltage (for example, about several tens KV to 100 KV) is applied between the high-pressure flange 20 and the ground flange 24, and the connecting line 28 is applied to the high-potential portion between them. Is exposed, there is a flashover between it and this connection line 28, which triggers a high flashover between the high pressure flange 20 and the grounding flange 24. There is. By the way, if such a flashover occurs, the stable operation of the ion source is hindered.

On the other hand, there is an idea to cover the connecting wire 28 by passing it through, for example, an insulating tube made of ceramics, but even in that case, a joint of the insulating tube is formed at the bent portion of the connecting wire 28, and the connection is made from there. Since the line 28 is exposed, there is a high risk that the flashover mentioned above will occur from that part, and this cannot be completely prevented.

In particular, the risk of flashover as described above increases as the voltage applied between the high-pressure flange 20 and the ground flange 24 increases.

Therefore, the main object of the present invention is to provide an ion source which eliminates the above-mentioned risk of flashover in the extraction electrode system.

[Means for Solving the Problems]

In order to achieve the above object, the ion source of the present invention is such that an insulating tube is passed through a side wall portion of a support frame as described above, the connecting wire is passed through the insulating tube, and a peripheral portion of the negative electrode is provided.
It is characterized in that a metal cover is attached to cover at least the vicinity of the connection portion between the negative electrode and the connection line.

[Action]

According to the above structure, the connection line for applying a negative voltage to the negative electrode and the connection portion between the high voltage flange and the ground flange and the other parts are not exposed in the high potential portion.

As a result, there is no risk of flashover between the high-potential portion and the connecting wire or the like, and thus between both flanges.

〔Example〕

FIG. 1 is an enlarged sectional view partially showing an example of a specific structure around the extraction electrode system of the ion source according to the present invention.
The same or corresponding parts as those in the examples of FIGS. 2 and 3 are designated by the same reference numerals, and the differences from the conventional example will be mainly described below.

In this embodiment, the thickness of the side wall portion 32a of the support frame 32 that supports the ground electrode 14 as described above is increased, and the insulating tube 34 made of, for example, ceramics is provided in the longitudinal direction thereof.
Both ends thereof are penetrated so as to be exposed from the side wall portion 32a to some extent.

The side wall portion 32a of the support frame 32 preferably has a uniform thickness over the entire circumference from the viewpoint of not disturbing the electric field distribution in the vicinity thereof.

Further, the current introducing terminal 26 described above is arranged on the downstream side (as viewed in the extraction direction of the ion beam 16) from the mounting portion of the support frame 32 and the grounding flange 24.

The current introducing terminal 26 (more specifically, the conductor
26b) and the negative electrode 13 (more specifically, the terminal 30 attached to the negative electrode 13) are connected to each other through a connecting wire 28 which passes through the insulating tube 34.

Further, a metal cover 36 is attached to the peripheral portion of the negative electrode 13 so as to cover at least the vicinity of the connecting portion between the negative electrode 13 and the connecting wire 28.

The cover 36 is preferably provided over the entire circumference of the negative electrode 13 from the viewpoint of not disturbing the electric field distribution in the vicinity thereof.

Further, in this embodiment, for example, a metal that is attached to the lower end of the support frame 32 and is set to the ground potential so that the vicinity of the connection portion between the current introduction terminal 26 and the connection line 28 is not exposed to the ion beam 16 side. It is covered with a cover 38.

The cover 38 is also preferably provided on the entire circumference along the support frame 32 from the viewpoint of not disturbing the electric field distribution in the vicinity thereof.

According to the above structure, the high pressure flange 20 and the ground flange
The connection line 28 and the connection between the connection line 28 and other objects (the negative electrode 13 and the current introduction terminal 26) are not exposed at all in the high potential portion between the vicinity of 24.

As a result, there is no risk of flashover between the high-potential portion and the connection line 28 or the like, and in the vicinity of both flanges. Therefore, the stability of the operation of the ion source is improved.

Further, the provision of the cover 38 is not essential for preventing flashover as described above, but if it is provided as in this embodiment, the negative potential portion is not exposed to the ion beam 16, There is no concern that the ion beam 16 will be partially attracted to the negative potential portion and its uniformity will be deteriorated.

Note that the above-described electrode configuration of the extraction electrode system 10 is an example, and other electrode configurations can be adopted. For example, another positive electrode is provided between the positive electrode 12 and the plasma source unit 2, and an ion beam is provided between the positive electrode and the positive electrode 12.
A so-called two-stage accelerating structure may be formed by constructing the extraction portion of 16 and accelerating the ion beam 16 between the positive electrode 12 and the ground electrode 14.

[Effect of device]

As described above, according to the present invention, the connection wire for applying a negative voltage to the negative electrode and the connection portion with other objects are exposed at the high potential portion between the high voltage flange and the ground flange. Since it disappears, there is no risk of flashover between the high-potential portion and the connecting wire or the like, and in the vicinity of both flanges. As a result, the stability of the operation of the ion source is improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view partially showing an example of a specific structure around the extraction electrode system of the ion source according to the present invention.
FIG. 2 is a schematic diagram showing a basic configuration example of an ion source. FIG. 3 is an enlarged sectional view partially showing a conventional example of a specific structure around the extraction electrode system of the ion source of FIG. 2 ... Plasma source part, 10 ... Extraction electrode system, 12 ... Positive electrode, 13 ... Negative electrode, 14 ... Ground electrode, 16 ... Ion beam, 20
… High-pressure flange, 24… grounding flange, 26… current introducing terminal, 28… connecting wire, 32… supporting frame, 34… insulating tube, 36,38… cover.

Claims (1)

[Scope of utility model registration request] 1. A plasma source part for producing plasma, and an ion beam extracted from the plasma source part, the positive electrode having a positive potential, the negative electrode having a negative potential, and the ground electrode having a ground potential. And a positive electrode, the positive electrode is attached to a high-voltage flange to which a positive high voltage is applied, and the ground electrode is supported by a metal support frame from a ground flange at a ground potential. And in the ion source having a structure in which it is connected to the negative electrode through a connection line through a current introducing terminal to the ground flange,
An insulating tube is passed through the side wall portion of the support frame, the connecting wire is passed through the insulating tube, and the peripheral portion of the negative electrode is made of metal that covers at least the vicinity of the connecting portion between the negative electrode and the connecting wire. An ion source characterized by having a cover attached.