JPH0831359B2 - Quadrupole particle accelerator and operating method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a quadrupole particle accelerator and an operating method thereof, and particularly to a quadrupole particle accelerator suitable for accelerating various ions, And its operating method.

[Conventional technology]

A conventional quadrupole particle accelerator is disclosed in, for example, JP-A-60-1151.
It is disclosed in Japanese Patent Publication No. 99.

This conventional quadrupole particle accelerator will be described with reference to FIG. As shown in the figure, the quadrupole electrodes 1, 2, 3, and 4 are insulated from the accelerating tube 5 via an insulator 6. Further, a resonance circuit including a coil 8 having an inductance L and a variable capacitor 7 having a capacitance C is installed outside the acceleration tube 5. The output of the oscillator 11 is
After being amplified at 10, it is supplied through the coupling coil 9.

Thus, even if the ion species changes, the output energy can be arbitrarily determined by changing the frequency accordingly.

[Problems to be Solved by the Invention]

However, in the conventional quadrupole particle accelerator described above, the DC potentials of the four quadrupole electrodes 1, 2, 3, and 4 are forcibly set to the ground potential, and the DC potential is set to an arbitrary potential. It wasn't adjustable. In other words, the above-mentioned prior art does not consider practical adjustment (accelerating voltage of the ion source, generated voltage of the quadrupole electrode, etc.) when accelerating various ions. In that case, there was a problem that the incident ion beam current to the quadrupole particle accelerator was significantly reduced.

The present invention has been made in view of the above points, and its object is to reduce the incident ion beam current to the quadrupole particle accelerator even when accelerating various ions. It is an object of the present invention to provide a quadrupole particle accelerator that can always obtain the maximum ion beam current for each ion species, and an operating method thereof.

[Means for solving the problem]

In the present invention, in order to achieve the above object, a quadrupole electrode having a structure in which an accelerating tube is provided with an insulator interposed therebetween, and the surfaces facing each other are wavy, and a DC variable power source having a ground potential via a choke coil When operating the quadrupole particle accelerator connected to the quadrupole particle accelerator or the quadrupole particle accelerator having a structure in which the facing surfaces of the quadrupole electrodes are corrugated, It is characterized in that the electric potential is adjusted to an arbitrary DC electric potential while maintaining the same electric potential so that the current value of the always incident beam can be maximized.

[Action]

If the quadrupole electrode can be adjusted to an arbitrary DC potential, the extraction voltage of the ion source that generates the ion beam incident on the quadrupole particle accelerator can be freely selected. Thereby, even when accelerating various ions, an optimum ion source extraction voltage can be set according to each ion source, and a maximum ion beam current can be obtained. The details will be described below.

When accelerating the ions with the quadrupole particle accelerator, it is necessary to change the energy of the ion beam incident on the quadrupole particle accelerator according to the change of the ion species. It is the extraction voltage of the ion source that determines this incident ion energy. If the mass number of ions is M and the charge number is e,
It is necessary to adjust the incident ion energy V _A in proportion to (M / e).

Therefore, each time the ion species is changed, V _A is adjusted using this proportional relationship. On the other hand, the extraction voltage of the ion source is the optimum value for each ion species to obtain the maximum and ion beam current from the relationship with the extraction current and the beam shape.
V _B exists and V _A and V _B generally do not match.

From the above background, in order to accelerate the quadrupole particle accelerator with the optimum V _B always set, the voltage V _C corresponding to the above difference between V _A and V _B is applied to the quadrupole electrode. It will be the case if it is applied. As a result, the maximum ion beam current can always be incident on the quadrupole particle accelerator.

〔Example〕

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

As shown in the figure, the quadrupole electrodes 1, 2, 3, and 4
Are insulated from the accelerating tube 5 via an insulator 6. A resonance circuit including a variable capacitor 7 and a secondary coil 8 is installed outside the acceleration tube 5.

Further, this resonance circuit is connected to the DC variable power supply 13 via the choke coil 12, and the quadrupole electrodes 1, 2,
The DC potentials of 3 and 4 as a whole can be arbitrarily set. The output of the oscillator 11 is the amplifier 10
After being amplified by, it is supplied to the resonance circuit through the primary coil 9. As a result, even when the ion species is changed, the DC potential can be set accordingly.

Therefore, the extraction voltage of the ion source can always be kept optimum, and the maximum ion beam current can always be obtained. The details will be described with reference to FIG.

As shown in the figure, the ions generated by the ion source 14 are
It is extracted by applying an acceleration voltage V _B to the ion extraction system 15.
The acceleration voltage V _B is a voltage when the incident ion beam 19 incident on the quadrupole particle accelerator 17 is maximized. on the other hand,
When a quadrupole particle incident ion energy required for acceleration determined by the shape of the quadrupole electrodes and V _A, the quadrupole electrodes, V _C
= It is sufficient to apply a voltage of V _B -V _A. With this method, the maximum ion beam current can be always accelerated while satisfying the acceleration condition, and the maximum accelerated ion beam 20 can be implanted in the ion implantation chamber 18.

Incidentally, by floating the quadrupole particle accelerator 17 from the installation potential in terms of DC potential, the ion deceleration system 16 is generated on the incident side of the quadrupole particle accelerator 17. This ion deceleration system 16 generally has a function of diverging an ion beam. In order to avoid this, it is apparent that inserting another focusing electrode kept at a negative potential is also effective as a means for not reducing the ion beam current.

Another embodiment of the present invention is shown in FIG. In the embodiment shown in the figure, a resonance circuit composed of a variable capacitor 7 and a secondary coil 8 is provided with a capacitor 20, and a quadrupole electrode 1, 2,
It is electrically insulated from 3 and 4 in a direct current manner, and a variable DC power supply 13 is connected to the quadrupole electrode side via a choke coil 12.

By doing so, the variable capacitor 7 and the secondary coil 8 can be installed in a DC manner, and the power input from the high frequency power source is structurally simpler than in the embodiment shown in FIG.

〔The invention's effect〕

According to the quadrupole particle accelerator of the present invention and the method of operating the same described above, it is possible to always operate the ion source in an optimum state, so that various ions are accelerated by the quadrupole particle accelerator. In this case, there is an effect that the maximum ion beam current can always be obtained for each ion species, and therefore, it can be applied as a high-current high-energy ion implanter in which the ion species and energy can be arbitrarily set.

[Brief description of drawings]

FIG. 1 is a diagram showing an electric circuit structure of an embodiment of a quadrupole particle accelerator of the present invention, and FIG. 2 is a potential when the quadrupole particle accelerator of FIG. 1 is applied to an ion implantation device. FIG. 3 is a distribution diagram, FIG. 3 is an electric circuit structure diagram showing another embodiment of the present invention, and FIG. 4 is a diagram showing an electric circuit structure of a conventional quadrupole particle accelerator. 1, 2, 3, 4 ... Quadrupole electrode, 5 ... Accelerator, 6 ...
Insulator, 7 ... Variable capacitor, 8 ... Secondary coil, 9
…… Primary coil, 10 …… Amplifier, 11 …… Oscillator, 12 ……
Choke coil, 13 ... DC variable power supply, 14 ... Ion source, 15 ... Ion extraction system, 16 ... Ion reduction system, 17 ...
… Quadrupole particle accelerator, 18 …… Ion implantation chamber, 19 ……
Incident ion beam, 20 …… accelerated ion beam, 21 …… condenser.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Noriyuki Sakudo 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hiritsu Manufacturing Co., Ltd. (56) Reference JP-A-1-137549 (JP, A) JP 60-115199 (JP, A) JP-A-60-121656 (JP, A)

Claims (2)

[Claims] 1. An accelerating tube, a quadrupole electrode having an undulating structure provided on the accelerating tube via an insulator and facing each other, and at least a secondary coil installed outside the accelerating tube. A quadrupole particle accelerator including a circuit component including one quadrupole electrode, wherein the quadrupole electrode is connected to a DC variable power source at a ground potential via a choke coil. Particle accelerator. 2. When operating a quadrupole particle accelerator having a structure in which the surface facing the quadrupole electrode is corrugated, the potential of the four electrodes of the quadrupole electrode is kept at the same potential. A method for operating a quadrupole particle accelerator, characterized in that the current value of an always-incident beam can be maximized by adjusting it to a DC potential.