JPH06243998A - High frequency quadrupole accelerator - Google Patents

Abstract

PURPOSE:To provide a high frequency quadrupole accelerator having a quadrupole electrode support structure by which quadrupole electrodes can be arranged accurately in a cage body and replacing work can be carried out easily. CONSTITUTION:Quadrupole electrodes 1, 2, 3 and 4 are supported with a plurality of the first and the second electrode holders 18 and 19, and are assembled integrally in a condition of securing positional accuracy between the electrodes. The quadrupole electrodes 1, 2, 3 and 4 in a condition of being supported with the first and the second electrode holders 18 and 19 are housed in a cage body 16, and the first and the second electrode holders 18 and 19 are supported with a plurality of the first and the second outer peripheral holders 20 and 21 fixed to prescribed positions in the cage body 16, so that the quadrupole electrodes 1, 2, 3 and 4 are arranged accurately in the cage body 16. Even replacing work of the quadrupole electrodes 1, 2, 3 and 4 is carried out similarly in a condition of the quadrupole electrodes 1, 2, 3 and 4 supported with the first and the second electrode holders 18 and 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle accelerator using a high frequency quadrupole electrode, and more specifically, an electrode capable of precisely supporting a quadrupole electrode arranged in a housing at a predetermined position. The present invention relates to a high frequency quadrupole accelerator having a support structure.

[0002]

2. Description of the Related Art For example, in order to obtain a high-energy ion beam for performing ion implantation, material analysis, etc., four vane electrodes (quadrupole electrodes) are placed in a resonant cavity as an accelerator using a high frequency electric field. The housed high frequency quadrupole accelerator is used. This high frequency quadrupole
The basic structure and operation of an adrupole accelerator (hereinafter referred to as RFQ) will be described below. RFQ shown in FIG.
The reference numeral 30 is configured by arranging electrodes 1, 2, 3, 4 forming a quadrupole electrode in a central axis direction of a cylindrical casing 5. The electrodes 1, 2, 3 and 4 are formed in a corrugated shape in which the surfaces facing each other are corrugated, and the concavo-convex shape is formed in the same phase in the electrodes facing each other and the concavo-convex shape in the electrodes adjacent to each other. Are formed in opposite phases. When a high-frequency voltage of the same phase is applied to the electrodes facing each other as shown in FIG. 5 and the opposite phase is applied to the electrodes adjacent to each other, as shown in FIG. , 3, 4
A quadrupole electric field is generated in the vicinity of the central axis facing each other. When the electrodes 1 and 3 are positive, the electrodes 2 and 4 are negative, and when the former is negative, the latter is positive. In addition to these conditions, since the concavo-convex shapes of the electrodes 1, 2, 3, 4 are vertically and horizontally shifted by 180 degrees, for example, the electrodes 1, 3 are positive and the electrodes 2, 4 are negative. Then, an axial electric field is generated on the central axis. When the voltage polarities of the electrodes 1, 2, 3, 4 are reversed, the direction of this electric field is also reversed. Now, if the ions injected into the quadrupole electrode along the central axis have such a velocity and phase that they always receive an accelerating electric field in the left-right direction, the electrodes 1, 2, 3,
The energy is monotonically increased as it is accelerated every time it passes through the uneven portion 4 of FIG. On the other hand, the ions that first enter the phase that undergoes deceleration are gradually bunched into the subsequent ions at the time of the next acceleration electric field, and are then monotonically accelerated. In addition, a strong high-frequency electric field existing in a plane orthogonal to the axis causes a strong focusing force in the vertical and horizontal directions, so that the ions can be accelerated with a very high transmittance. In reality, a transport efficiency close to 100% can be obtained for the first time by designing a quadrupole electrode in which the ion velocity increases, the period of the unevenness and the electrode interval are gradually changed according to the bunching situation. In order to exhibit the above-described acceleration performance in RFQ, it is required that each of the electrodes 1, 2, 3 and 4 forming the quadrupole electrode be accurately fixed at predetermined positions. FIG. 6 shows an example of a conventional configuration for fixing the electrodes 1, 2, 3, 4 in the housing 5. As shown, electrode holders 6 and 6 that support electrodes 1 and 3 that face each other in the horizontal direction and electrodes 2 and 4 that face each other in the vertical direction
The electrode holders 7, 7 for supporting the lower flat seat 1 fixed to the lower portion of the housing 5a by the lower supporters 8 are arranged alternately at predetermined intervals in the central axis direction of the housing 5a.
0, and the electrode holders 7, 7 are connected to the upper flat seat 11 fixed to the upper part of the casing 5a by the upper supporter 9, so that the electrodes 1, 2, 3, 4 are connected to the central axis of the casing 5a. Fixed in the direction. With this configuration, each electrode 1,
In order to ensure the positional accuracy of 2, 3, and 4, the electrode holders 6 and 7, the supporters 8 and 9, and the flat seats 10 and 11 are processed with high accuracy with an error of several tens of μm, and the adjustment jig is used. The accuracy is ensured by adjusting the electrode position accuracy within an error of about ± 25 μm over the entire length.

[0003]

To ensure the accuracy of the disposition position of the quadrupole electrode, it is very difficult to manufacture it because it requires high-precision machining of the mounting member and precise assembly work as described above. ， There was a problem that the cost and the time became large. Further, when the RFQ is used as an ion implanter for a semiconductor process, it is required to convert the ion species and the ion beam velocity. In such a case, an accelerating electrode replacement type RFQ that can be replaced with a quadrupole electrode suitable for the purpose of use is desired. However, in the RFQ having the conventional configuration, it is not easy to attach / detach the quadrupole electrode to / from the electrode holder fixed in the housing, and the workability is poor and the working time is long.
There is a problem that the device is easily damaged due to difficult working conditions. The present invention was made in view of the above problems, and a high-frequency quadrupole having a quadrupole electrode supporting structure that allows accurate placement of the quadrupole electrode in the housing and facilitates replacement work. An object is to provide a polar electrode accelerator.

[0004]

In order to achieve the above object, the present invention employs a quadrupole electrode in which two pairs of electrodes facing each other are arranged in a cross direction inside a cylindrical casing. In the central axis direction of the quadrupole electrode and applying high-frequency power to the quadrupole electrodes to accelerate charged particles passing between the quadrupole electrodes to an arbitrary speed. A plurality of first electrode holders that support a first electrode pair that is opposed to one direction of the electrode, and a plurality of first electrode holders that support a second electrode pair that is opposed to the other direction of the quadrupole electrode. Two electrode holders are alternately arranged at a predetermined interval in the central axis direction inside the housing, and a plurality of first outer peripheral holders supporting the first electrode holders and the second electrode holders A plurality of second outer peripheral holders that support the Be Te configured as a high-frequency quadrupole accelerator according to claim.

[0005]

According to the present invention, the quadrupole electrode is assembled integrally by being supported by the plurality of first and second electrode holders and in a state where the positional accuracy between the electrodes is secured. The quadrupole electrode in a state of being supported by the first and second electrode holders is housed in a housing, and the first and second outer peripheral holders fixed at predetermined positions in the housing are used to store the first and second electrodes. By supporting the second electrode holder, the quadrupole electrode is accurately arranged in the housing. Also in the replacement work of the quadrupole electrode, similarly, the quadrupole electrode supported by the first and second electrode holders is fixed to the first casing inside the casing.
And the work of attaching to and detaching from the second outer peripheral holder. Therefore, since the highly accurate assembly work of the quadrupole electrode can be performed outside the housing, the workability is good and the influence of the accuracy error on the housing side can be eliminated. Also, when replacing the quadrupole electrode, it is possible to improve the workability of the replacement and to reduce the work time by preparing and replacing the quadrupole electrode that is accurately supported by the first and second electrode holders in advance. Shortening and damage to the device are prevented.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. still,
The following example is an example embodying the present invention and does not limit the technical scope of the present invention. Figure 1
FIG. 2 is a perspective view showing an RFQ quadrupole electrode supporting structure according to an embodiment of the present invention, FIG. 2 is a front view of a first electrode holder position (a) and a second electrode holder position front view (B). 3 is a perspective view showing a state in which the quadrupole electrode is supported by the first and second electrode holders and integrally assembled. In FIG. 1, an RFQ 15 according to the present embodiment has electrodes 1, 2, 3, 4 arranged in the central axis direction so as to face each other around a central axis 14 of a cylindrical casing 16 that constitutes a resonance cavity. It constitutes a quadrupole electrode. The electrodes 1, 2, 3, 4 have a central axis 1
First electrode holders 18, 18 alternately arranged in four directions
And the second electrode holders 19, 19.
As shown in FIG. 2A, the first electrode holder 18 has a rectangular opening in which the long sides supporting the electrodes 1 and 3 (first electrode pair) are formed in the vertical direction in the drawing. 1, 3 are attached to the predetermined positions of the long sides with knock pins or the like, and electrodes 2,
No. 4 is penetrated without contact. As shown in FIG. 2B, the second electrode holder 19 has a rectangular opening in which long sides for supporting the electrodes 2 and 4 (second electrode pair) are formed in the horizontal direction in the drawing. 2, 4 are attached to predetermined positions on the long side by knock pins or the like, and the electrodes 1, 3 are penetrated without contact. The first electrode holder 18 and the second electrode holder 19 are each formed in a square outer shape, and the first frame is formed with an inner frame capable of providing a space of several mm around the outer shape.
Are supported by the outer peripheral holder 20 and the second outer peripheral holder 21, respectively. The support of the electrode holders 18 and 19 by the outer peripheral holders 20 and 21 is connected by joint screws 17 and 17 as shown in the figure so that the support position can be finely adjusted. First outer peripheral holder 20, 2
0 is attached to the lower flat seat 23 fixed to the lower surface of the housing 16 by the supporter 22. Similarly, the second outer peripheral holders 21 and 21 are attached to the upper flat seat 24 fixed to the upper surface of the housing 16 by the supporters 22. With the above configuration, the electrodes 1 and 3 are provided on the upper surface of the housing 16, and the electrodes 2 and 3 are
4 is also electrically connected to the lower surface of the housing 16, the peripheral surface of the housing 16 serves as an inductor, and a resonance cavity in which a resonant circuit is formed in the housing 16 together with a separately configured capacitor, A description of the electrical configuration is omitted. The electrodes 1, 2, 3 and 4 and the first and second electrode holders 18 and 19 that support the electrodes in the above-described configuration are integrally assembled as shown in FIG. Be accommodated. At this time, the first electrode holders 1 alternately arranged
8 and 18 and the second electrode holders 19 and 19 are connected and supported by the support rod insertion holes 25 provided in the electrode holders 18 and 19 as shown in FIG.
Is inserted to secure the connection rigidity until the housing 16 is housed. In the integrally assembled state as shown in FIG. 3, the positional accuracy of the electrodes 1, 2, 3, 4 is adjusted within an error of ± 25 μm using an adjustment jig. It is needless to say that this assembling and precision adjusting work can be performed in a free space outside the housing 16 unlike the conventional work, so that workability is significantly improved.

Assembled integrally as described above,
The electrodes 1, 2, 3, 4 and the electrode holders 18, 19 in which the precision is adjusted are inserted into the housing 16, and the outer peripheral holders 20, 21 are fixed in position by joint screws 17 and joints are formed. The screws 17, electrodes 1, 2, 3,
4 is adjusted to fit in place. After that, by pulling out the support rods 26, 26, the electrodes 1, 2, 3,
The mounting of No. 4 in the housing 16 is completed. With the above configuration, the accuracy of the spacing between the electrodes 1, 2, 3, 4 is ensured, and the housing 1
Since the installation position in 6 can be adjusted by the joint screw 17, each outer holder 20, 21 or supporter 2
2. The processing and assembling accuracy of the lower flat seat 23 and the upper flat seat 24 is relaxed to about ± 1 mm. By the way, the RFQ capable of efficiently converging and accelerating charged particles is used in a semiconductor process, which has recently been highly demanded. For example, when ion implantation is performed on a semiconductor substrate, an ion beam from an ion source can be injected between the quadrupole electrodes to accelerate it to an arbitrary speed. When it is used for ion implantation for such a semiconductor process,
It is required that the ion species and ion beam velocity can be selected. As for ion acceleration, a transport efficiency close to 100% can be obtained by an electrode design in which the period of concavities and convexities formed on the quadrupole electrode and the electrode interval are changed according to the increase in ion velocity and bunching conditions. Therefore, in order to meet the above requirements,
There is a demand for an electrode exchange type RFQ that can be exchanged for a quadrupole electrode designed to meet the purpose. However, as described above, it is not easy to replace the quadrupole electrode in the RFQ having the conventional configuration. Electrode exchange type RF
It will be already understood that the RFQ having the configuration of this embodiment is suitable for being adopted as the Q. If I dare to explain, the procedure is as follows. The electrodes 1a, 2a, 3a and 4a to be attached for replacement are assembled on the electrode holders 18a and 19a as shown in FIG. 3 and prepared in a state where the accuracy is adjusted. Next, after inserting the support rod 26b into each of the electrode holders 18b and 19b in the housing 16, loosening the joint screw 17 and then each of the electrode holders 18b and 19b.
The electrodes 1b, 2b, 3b and 4b are pulled out together with 19b.
After that, the electrodes 1a, 2a, which are integrally assembled and prepared,
3a, 4a and each electrode holder 18a, 19a
It is inserted into the inside and attached to each outer circumference holder 20, 21. After the installation positions of the electrodes 1a, 2a, 3a, 4a are adjusted,
The exchange work is completed when the support rod 26a is pulled out. In this electrode exchange, since the electrode interval is already adjusted in the preparatory stage, there is no need for highly difficult work for finely adjusting the precision in the housing 16, and workability and work time are greatly improved. Although the cavity resonance type RFQ has been described in the present embodiment, it can be similarly applied to an external resonance type RFQ having a resonance circuit outside the housing.

[0008]

As described above, according to the structure of the RFQ according to the present invention, the quadrupole electrode is integrally supported by being supported by the plurality of first and second electrode holders, and the position between the electrodes can be improved. It is assembled in a state where accuracy is secured. The quadrupole electrode in a state of being supported by the first and second electrode holders is housed in a housing, and the first and second outer peripheral holders fixed at predetermined positions in the housing are used to store the first and second electrodes. By supporting the second electrode holder, the quadrupole electrode is accurately arranged in the housing. Moreover, also in the replacement work of the quadrupole electrode, the first and second supporting quadrupole electrodes are similarly supported.
This is done by attaching and detaching the electrode holder to and from the first and second outer peripheral holders fixed in the housing.
Therefore, since the highly accurate assembly work of the quadrupole electrode can be performed outside the housing, the workability is good and the influence of the accuracy error on the housing side can be eliminated. Also, when replacing the quadrupole electrode, it is possible to improve the workability of the replacement and to reduce the work time by preparing and replacing the quadrupole electrode that is accurately supported by the first and second electrode holders in advance. Shortening and damage to the device are prevented.

[Brief description of drawings]

FIG. 1 is a perspective view showing an RFQ quadrupole electrode support structure according to an embodiment of the present invention.

FIG. 2 is a front view (a) of a first electrode holder installation position and a front view (b) of a second electrode holder installation position according to the embodiment.

FIG. 3 is a perspective view showing a state in which the quadrupole electrode according to the embodiment is supported by first and second electrode holders and integrally assembled.

FIG. 4 is a perspective view of an RFQ according to a conventional example.

FIG. 5 is a schematic diagram illustrating the operating principle of a quadrupole electrode.

FIG. 6 is a perspective view showing a support structure for a quadrupole electrode according to a conventional example.

[Explanation of symbols]

 1, 3 ... Electrode (first electrode pair) 2, 4 ... Electrode (second electrode pair) 14 ... Central axis 15 ... Radio frequency quadrupole accelerator (RFQ) 16 ... Housing 18 ... First electrode holder 19 ... 2nd electrode holder 20 ... 1st outer periphery holder 21 ... 2nd outer periphery holder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Furukawa 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Institute of Technology, Kobe Steel Co., Ltd. (72) Satoshi Suzuki Takatsuka, Nishi-ku, Kobe-shi, Hyogo Prefecture 1-5-5 stand, Kobe Steel, Ltd. Kobe Research Institute

Claims (1)

[Claims] 1. A quadrupole electrode in which two pairs of electrodes facing each other are arranged in a cross direction is arranged in a central axis direction inside a cylindrical casing, and high frequency power is applied to the quadrupole electrode. In a high-frequency quadrupole accelerator for accelerating charged particles passing between quadrupole electrodes to an arbitrary speed, a plurality of first electrode pairs that are arranged to face each other in one direction of the quadrupole electrodes are supported. A first electrode holder and a plurality of second electrode holders supporting a second electrode pair arranged opposite to each other in the other direction of the quadrupole electrode are alternately arranged at predetermined intervals in the central axis direction inside the casing. And a plurality of first outer peripheral holders that support the first electrode holders and a plurality of second outer peripheral holders that support the second electrode holders are alternately arranged in the housing. A high-frequency quadrupole accelerator characterized by being fixed at intervals.