JPH0619961B2 - Microwave ion source - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a microwave ion source, and more particularly to a microwave ion source suitable for a high-current ion implanter capable of extracting a mA-class ion beam.

[Background of the Invention]

 FIG. 1 shows the configuration of a conventional microwave ion source.

In the conventional microwave ion source, the air-core solenoid coil 8 for generating a magnetic field in the discharge chamber 5 is placed at the ground potential position, and the potential of the discharge chamber 5 becomes the same potential as the accelerating potential of the extracted ion beam 21. It was placed. For this reason, there is a drawback that a magnetic field exists in a space to which an electric field for extracting the ion beam 21 is applied, and abnormal discharge between the extraction electrodes easily occurs in this space. Also, the discharge chamber 5
Since the air-core solenoid coil 8 needs to be electrically insulated (for example, withstand voltage of 80 KV), it has to be placed at a large distance. Therefore, the air-core solenoid coil 8 is inevitably large, and there is a drawback that the applied power is large.

[Object of the Invention]

It is an object of the present invention to provide a microwave ion source that makes it difficult for an abnormal discharge to occur in a space for extracting an ion beam and that can generate a magnetic field generated in a discharge chamber with low power.

[Outline of Invention]

The absence of a magnetic field in the space for extracting the ion beam, and bringing the magnetic field generator near the discharge chamber are solutions to the above object.

In the present invention, a permanent magnet or an electromagnet for generating a magnetic field in the discharge chamber is placed at the same potential as the discharge chamber,
The discharge chamber is surrounded by a magnetic path of a high magnetic permeability member so that a magnetic field is generated only near the discharge chamber and no magnetic field is generated in the space for extracting the ion beam.

Example of Invention

 An embodiment of the present invention will be described below with reference to FIG.

As shown in the figure, the microwave ion source includes a microwave generator 1, a waveguide 2, a microwave introduction flange 3, a discharge chamber 5, a gas introduction tube 6, a magnetic field generator 8, and an ion beam extraction electrode system 7. It is configured.

Microwaves generated by the microwave generator 1 are introduced into the discharge chamber 5 via the rectangular waveguides 2a and 2b and the microwave introduction flange 3, and a microwave electric field is generated in the discharge chamber 5. Further, in the vicinity of the discharge chamber 5, a solenoid coil 8a placed so as to surround the discharge chamber 5 and a magnetic path 8 made of pure iron.
b, auxiliary magnetic pole 8 for controlling the magnetic field distribution in the discharge chamber 5
The magnetic field generator composed of c applies a magnetic field in a direction orthogonal to the microwave electric field. In this state, the gas to be ionized is introduced into the discharge chamber 5 through the gas introduction pipe 6, and the interaction between the microwave electric field and the magnetic field formed in the discharge chamber 5 causes plasma to be generated and the ion beam to be extracted. An ion beam 21 is extracted from the plasma by the electrode systems 7a, 7b, 7c.

According to the present embodiment, the leakage of the magnetic field into the ion beam extraction space can be suppressed to several Gauss or less (at 600 Gauss in the discharge chamber), and the abnormal discharge is less likely to occur in the ion beam extraction space. The ion beam can be easily extracted. Also, the solenoid coil 8a
Conventionally, the electric power to be applied to 1,200 W has been required to be about 1200 W, whereas the electric power to be applied is 300 W or less, and the magnetic field generated in the discharge chamber can be generated with low electric power.

〔The invention's effect〕

According to the microwave ion source of the present invention described above,
It is possible to reduce abnormal electric discharge in the ion beam extraction space and also reduce electric power supplied to the magnetic field generator.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a conventional microwave ion source, and FIG. 2 is a sectional view showing an embodiment of the microwave ion source according to the present invention. 1 ... Microwave generator, 2a, 2b ... rectangular director,
3 ... Microwave introduction flange, 4 ... Discharge electrode, 5 ...
... Discharge chamber, 6 ... Gas introduction tube, 7a, 7b, 7c ... Ion beam extraction electrode system, 8, 8a ... Solenoid coil, 8b ... Magnetic path, 8c ... Auxiliary magnetic pole, 11 ... In discharge electrode A dielectric filling for forming a discharge chamber in
… Insulators.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takayoshi Seki, 1-280 Higashi Koigakubo, Kokubunji City, Tokyo Metropolitan Research Laboratory, Hitachi, Ltd. (72) Inventor Susumu Kosasa 1-280 Higashi Koigakubo, Kokubunji City, Tokyo Hitachi, Ltd. In the Central Research Laboratory (72) Inventor, Shuji Okada 1-280, Higashi Koigakubo, Kokubunji City, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. (56) References Sponsored by Ion Engineering Conference, June 7th to June 9th, 1982, Proceedings for the 6th symposium entitled "Ion Source and Applied Technology Based on Ions" held at Hideyo Noguchi Memorial Hall, Tokyo, co-sponsored by The Institute of Electrical Engineers, Electronic Devices Technical Committee Published June 6, 1957). P. 25-28

Claims (2)

[Claims] 1. A microwave ion source for extracting ions from plasma produced by the action of an electric field generated by microwaves and a magnetic field generated by a permanent magnet or an electromagnet, wherein a permanent magnet or an electromagnet for generating the magnetic field is used. , The magnetic field is generated only in the vicinity of the discharge chamber where the plasma is formed, and the magnetic field is generated only in the vicinity of the discharge chamber, and the magnetic field is not generated in the space for extracting the ion beam. A microwave ion source characterized by being surrounded by a magnetic path of a member. 2. The auxiliary magnetic pole for controlling the magnetic field distribution inside the discharge chamber is attached to the tip of the magnetic path formed of the high magnetic permeability member. Microwave ion source.