JPH1064437A - Ion beam generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform plasma distribution for the front surface of a beam extraction grid electrode, and make the extracted ion beam nondeflecting and even. SOLUTION: In the ion beam generating device where vacuum arc discharge is made to take place between an anode 1 and each of a plurality of metallic cathodes 3 so as to allow an ion beam to be extracted, a plurality of metallic cathodes 3 are provided at positions symmetric with respect to the axial line A of an ion source, so that vacuum arc discharge are made to take place simultaneously at a plurality of the metallic cathodes 3 located in the symmetrical positions. Furthers, the metallic cathodes 3 are so provided that the axial line B of each cathode is directed toward the center of a grid electrode, and concurrently a magnetic field 33 perpendicular to the grid electrode is so applied to a space between the anode and the grid electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam generator.

[0002]

2. Description of the Related Art As shown in FIGS. 8 and 9, an ion beam generator is provided with an anode 51 and a plurality of metal cathodes 52 installed in a vacuum and insulated from each other. Acceleration grid 53 and suppressor grid 54 which are grid electrodes for extraction
And a ground grid 55 in which a vacuum arc discharge is caused between the anode 51 and the plurality of metal cathodes 52 to extract an ion beam.

However, in this type of conventional ion beam generator, as shown in FIG.
Are arranged at equal intervals in the circumferential direction, and the anode 5
One is a plurality of openings 56 corresponding to each metallic cathode 52.
Each metallic cathode 52 is provided so as to be deviated from the center position of the beam extraction grid electrode due to its configuration (for example, Japanese Patent Application Laid-Open No. 5-205683).

[0004]

In the prior art, since a plurality of metal cathodes 52 are provided so as to be deviated from the center position of the beam extraction grid electrode, the extracted ion beam also depends on the deviation of the metal cathode 52. As a result, the ion source is deviated from the axis A, and as a result, the ion implantation amount into the object to be processed irradiated with the ion beam is deviated, and there is a problem that uniform reforming characteristics cannot be obtained.

In view of the above problems, the present invention provides a uniform plasma distribution on the front surface of a grid electrode for extracting a beam, so that the extracted ion beam can be made uniform without deviation.

[0006]

A first technical means of the present invention for solving this technical problem is to extract an ion beam by causing a vacuum arc discharge between an anode 1 and a plurality of metal cathodes 3. In such an ion beam generator, a plurality of metal cathodes 3 are provided at positions symmetrical with respect to the axis A of the ion source, and a vacuum arc discharge is caused simultaneously at the plurality of metal cathodes 3 at symmetrical positions. On the point.

[0007] The second technical means of the present invention is the anode 1
And a plurality of metal cathodes 3. In the ion beam generator, a vacuum arc discharge is generated alternately to extract an ion beam. The cathode axis B of the metal cathode 3 is directed toward the center of the grid electrode. And a magnetic field 33 perpendicular to the grid electrode is applied between the anode and the grid electrode.

Therefore, the generated metal plasma is due to vacuum arc discharge generated between a plurality of metallic cathodes 3 and anodes 1 provided at positions symmetrical with respect to the ion source axis A. From this, a uniform plasma distribution 24 is generated as a whole, and its ion beam distribution 2
6 is uniform without any bias. Further, since the metallic cathode 3 is inclined such that the cathode axis B is directed toward the center of the grid electrode, the center of the plasma density distribution 24 generated by the vacuum arc discharge can be aligned with the center of the grid electrode. The plasma is trapped by the magnetic field 33 perpendicular to the grid electrode, and the traveling direction of the ions is perpendicular to the grid electrode. As a result, an unbiased ion beam distribution 26 is obtained.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 1 denotes an anode, and two openings 2 are provided. Reference numeral 3 denotes a metallic cathode, two of which are provided symmetrically with respect to the ion source axis A. Each metallic cathode 3 and the anode 1
Are located at positions corresponding to each other. An insulating material 4 is fitted on each metal cathode 3 and connected to a trigger electrode 7 via a trigger ring 6.

Reference numeral 9 denotes an arc power supply for applying a voltage between the anode 1 and each metallic cathode 3. A trigger power supply 10 instantaneously applies a high voltage between each metallic cathode 3 and each trigger electrode 7. 12 is an acceleration grid, 13
Is a suppressor grid, and 14 is a ground grid, which constitutes a grid electrode for extracting a beam. Reference numeral 17 denotes an acceleration power source which holds the acceleration grid 12 and the anode 1 at a high voltage of several KV to several hundred KV. Reference numeral 18 denotes a suppressor power supply for applying a negative voltage to the suppressor grid 13. The ground grid 14 is grounded.

According to the configuration of the above embodiment, the metallic power source 3 and the trigger electrodes 7
, A trigger discharge is generated between each trigger ring 6 and the metallic cathode 3. This trigger discharge triggers a vacuum arc discharge between the anode 1 and each metallic cathode 3. Due to the occurrence of the vacuum arc discharge, a point called a cathode spot where energy is concentrated appears at the tip of the cathode 3, and the material in this portion evaporates and ionizes to generate metal plasma.

The generated metal plasma is guided from the discharge region 20 between the metallic cathode 3 and the anode 1 to the plasma chamber 21 through the opening 2 of the anode 1. This metal plasma is generated by a vacuum arc discharge generated between two metallic cathodes 3 and anodes 1 provided at positions symmetrical with respect to the ion source axis A. First metal plasma density distribution 24a due to vacuum arc discharge generated between cathode 3 and anode 1
And the second metal plasma density distribution 24b due to the vacuum arc discharge generated between the other metallic cathode 3 and the anode 1 are superimposed, resulting in a uniform plasma distribution 24 as a whole.

The metal ion beam 25 guided to the plasma chamber 21 is accelerated by the electric field between the grids, passes through the grid opening, and is drawn out to the processing chamber 23, and its ion beam distribution 26 is uniform without deviation. become. Here, the suppressor grid 13 prevents free electrons existing in the processing chamber 23 from flowing back to the plasma chamber 21. FIG. 3 shows another embodiment, in which a metallic cathode 3 (3A,
3B, 3C, 3D, 3E, 3F) are provided at equal intervals in the circumferential direction, and a trigger switch 29 is provided. The trigger switch 29 allows the metal at a position symmetrical with respect to the ion source axis A. Of metallic cathode 3A and metallic cathode 3D, metallic cathode 3B and metallic cathode 3E
Or the set of the metallic cathode 3C and the set of the metallic cathode 3F, and the trigger power supply 10 simultaneously applies between the two metallic cathodes 3 of the selected set and the corresponding trigger electrode 7. By instantaneously applying a high voltage, a trigger discharge is simultaneously generated between the two metallic cathodes 3 and the anode 1 at positions symmetrical with respect to the ion source axis A. In this case, the plasma distribution becomes uniform, and the ion beam distribution becomes uniform without deviation.

In the case of FIG. 3, a set of a metallic cathode 3A, a metallic cathode 3C and a metallic cathode 3E or a metallic cathode 3B located at a position symmetrical with respect to the ion source axis A by the trigger switch 29. , Select one of the set of metallic cathode 3D and metallic cathode 3F,
The trigger power source 1 is simultaneously connected between the selected set of three metallic cathodes 3 and the corresponding trigger electrodes 7.
By instantaneously applying a high voltage by 0, a trigger discharge is simultaneously generated between the three metallic cathodes 3 and the anode 1 at positions symmetrical with respect to the ion source axis A. In this case as well, the plasma distribution becomes uniform, and the ion beam distribution becomes uniform without bias.

In the embodiment shown in FIG. 3, only the selected set of metallic cathodes 3 is used for generating an ion beam, and when the metallic cathode 3 is exhausted, the next set of metallic cathodes 3 is used. 3 may be selected for use in generating an ion beam, or a set of a plurality of metallic cathodes 3 located at positions symmetrical with respect to the axis A of the ion source may be sequentially and alternately subjected to vacuum arc discharge. And all the sets of metallic cathodes 3 may be used sequentially for the generation of an ion beam. In addition, each set of metallic cathodes 3
May be a metallic cathode of a dissimilar metal or a metallic cathode 3 of the same kind of metal.

FIG. 4 shows another embodiment, in which an arc power source 9 is provided for each metallic cathode 3 in order to ensure the occurrence of vacuum arc discharge at each metallic cathode 3. . Other points are the same as those in the embodiment of FIG. In the case of the embodiment of FIG.
When an arc power supply 9 is provided for each metallic cathode 3 in order to ensure the occurrence of a vacuum arc discharge at each metallic cathode 3 as in the embodiment of FIG. If a switch for the arc power supply is used as in the case of the device 29, only two arc power supplies 9 can be used together with the trigger power supply 7.

FIG. 5 shows another embodiment, in which the metallic cathode 3 is placed at a position symmetrical with respect to the ion source axis A.
In addition, each metallic cathode 3 is inclined such that its cathode axis B is directed toward the center of the grid electrode, and the anode 1 is bent in a V-shape so as to correspond to the inclination of the metallic cathode 3. . An annular electromagnetic coil 3 is provided between the anode 1 and the grid electrodes (the acceleration grid 12, the suppressor grid 13, and the ground grid 14).
1 and a coil power supply 32 for supplying power to the electromagnetic coil 31 is provided.
Thus, a magnetic field 33 perpendicular to the grid electrode is applied between the anode 1 and the grid electrode.

Unlike the embodiment shown in FIG. 5, each metallic cathode 3 is arranged so that its cathode axis B is parallel to the ion source axis A as shown in FIG. When the magnetic field 33 is not provided between the electrode and the electrode, as shown in FIG.
And the ion beam distribution 26 is also biased. On the other hand, in the case of the embodiment of FIG. 5, each metallic cathode 3 is inclined such that its cathode axis B is directed toward the center of the grid electrode.
As shown in (1), the center of the plasma density distribution 24 due to the plasma generated by the vacuum arc discharge can be aligned with the center of the grid electrode. Further, the plasma is captured by the magnetic field 33 perpendicular to the grid electrode, and the traveling direction of the ions becomes perpendicular to the grid electrode. as a result,
The bias of the plasma obtained from each cathode located at a position deviated from the center is eliminated, and the ion beam distribution 26 without deviation is obtained.

In the case of the embodiment shown in FIG. 5, the two metallic cathodes 3 may alternately generate a vacuum arc discharge by switching by the trigger switch 29, or two metallic cathodes may be used. The cathode 3 may be caused to cause vacuum arc discharge at the same time. The number of metallic cathodes 3 to be provided is not limited to two, but may be one or three.
More than two metallic cathodes 3 may be provided.

[0020]

According to the present invention, a uniform plasma distribution can be obtained on the front surface of the grid electrode for extracting a beam.
The extracted ion beam can be made uniform without deviation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a front view of the metallic cathode portion.

FIG. 3 is a configuration diagram showing another embodiment.

FIG. 4 is a configuration diagram showing another embodiment.

FIG. 5 is a configuration diagram showing another embodiment.

FIG. 6 is an explanatory diagram for explaining the operation.

FIG. 7 is an explanatory diagram for explaining the operation.

FIG. 8 is a sectional view showing a conventional example.

FIG. 9 is a sectional view taken along line AA of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode 3 Metallic cathode 12 Acceleration grid 13 Suppressor grid 14 Ground grid 33 Magnetic field

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Noriyuki Inuishi 2-3-1, Shinhama, Arai-machi, Takasago-shi, Hyogo Inside Kobe Steel, Ltd. Takasago Works

Claims (2)

[Claims] 1. An ion beam generator in which a vacuum arc discharge is generated between an anode (1) and a plurality of metal cathodes (3) to extract an ion beam. An ion beam generator, wherein a vacuum arc discharge is simultaneously generated in a plurality of metal cathodes (3) at symmetric positions with respect to a source axis A. 2. An ion beam generator wherein an arc beam is alternately generated between an anode (1) and a plurality of metal cathodes (3) to extract an ion beam. The cathode axis B is provided so as to face the center of the grid electrode, and a magnetic field (33) perpendicular to the grid electrode is applied between the anode (1) and the grid electrode. An ion beam generator.