JPH0668988A - Revolver type multi-rfq ion accelerator - Google Patents

Abstract

PURPOSE:To adjust the acceleration energy of ions by providing a plurality of RFQ ion acceleration parts radially around the rotation shaft extending in the passing direction of particles, and by storing the acceleration parts in a vacuum chamber so that the acceleration parts can be rotated freely. CONSTITUTION:Required ions are drawn from an ion source, accelerated by an RFQ ion accelerator 9, and are sent to an end station. A rotation shaft 14 is supported in the center of a cylindrical vacuum chamber 13 in the accelerator 9, and a base board 15 is provided in an integrated manner with the rotation shaft around the rotation shaft, so that they can be rotated freely. Ion acceleration parts 16-19 are provided in the longitudinal direction, on the four side surfaces of the base board 15. The acceleration parts 16-19 are formed by raising a support 5 for supporting a pair of rods 6 that are opposed to one another sandwiching a passing direction A of particles, and the support 5 for supporting a pair of rods 6, which crosses the rod 6, on the base board 15 in the longitudinal direction of the base board 15. The acceleration parts can be provided radially on the shaft 14, and are stored in the chamber 13 so that they can be rotated freely, and the ion acceleration energy can thus be adjusted freely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is an RFQ (Radio-Frequency-Qu) which is one type of high frequency particle accelerator.
adrupole).

[0002]

2. Description of the Related Art The RFQ ion accelerator is capable of easily accelerating large-current ions to the MeV order as compared with the conventional electrostatic accelerator, and the incident energy is smaller than that of a drift tube and the structure is relatively simple. Therefore, it is convenient as an ion accelerator for industrial ion implanters, analyzers and the like.

3 and 4 show an example of the structure of this RFQ ion accelerator. As shown, this RF
The Q ion accelerator 2 has a first support 5a and a second support 5b which are erected at a distance from each other on a base plate 4 in the chamber 1 which is evacuated, and an ion passage is provided in the first support 5a. A pair of rods 6a and 6d that face each other across A are supported, and a pair of rods 6b and 6c that face each other in a direction intersecting with the rods 6a and 6d are supported by the second support 5b. There is. Then, by supplying high-frequency power to this RFQ ion accelerator, the resonance current i flows through the first support 5a, the base plate 4 and the second support 5b, and the adjacent rod 6
An electric field is generated between a and 6d. In this state, the rod 6a-
When a particle beam is incident on the central portion of 6d (direction A in the figure), the beam is focused and accelerated by the quadrupole electric field between the rods 6a to 6d and emitted.

[0004]

By the way, the RFQ
Since the acceleration energy in is usually proportional to the square of the resonance frequency, it is essential to arbitrarily change the resonance frequency when applying RFQ to the ion implantation apparatus.
However, this resonance frequency has a geometrical dimension, that is, the path length of the resonance current i (twice the support height H and the distance D
The resonance frequency is fixed in the conventional RFQ, and can be changed arbitrarily because it is determined by the inductance L due to the sum of) and the capacitance C between the rods 6a to 6d. There wasn't.

Therefore, the number of required resonance frequencies is R.
Since it is necessary to adjust the acceleration energy of the ions by preparing an FQ or by providing one or more energy adjusting means such as a cavity resonator on the downstream side of the RFQ, the apparatus becomes large and the cost is reduced. There was a problem that it became very expensive.

Therefore, the present invention has been devised to effectively solve the above-mentioned problems, and the purpose thereof is to provide a revolver type multi-RFQ ion accelerator capable of adjusting the ion acceleration energy as needed. Is provided.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a first support for supporting a pair of rods facing each other across a passage of particles on a base, and intersecting the pair of rods. A plurality of RFQ ion accelerating parts, in which a second support supporting a pair of rods facing each other in a direction opposite to each other are alternately set up at a predetermined interval, are formed at different heights of the support, and a plurality of these RFQ ion accelerating parts are formed. Around the rotation axis extending the RFQ ion accelerating part of the above in the passage direction of the particles,
It is provided radially and is housed rotatably in a vacuum chamber.

[0008]

As described above, according to the present invention, a plurality of RFQ ion accelerating parts having different support heights are radially provided around the rotation axis and centered around the rotation axis, and are rotatably housed in the vacuum chamber. By doing so, an ion beam with a large amount of energy can be easily obtained. Further, it is possible to easily change to a desired RFQ ion accelerating unit simply by rotationally driving the rotating shaft.

[0009]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 shows a revolver type multi-RFQ according to the present invention.
1 shows an embodiment of an ion implanting device equipped with an ion accelerator. As shown in the figure, this ion implanter includes an evacuated ion source (IS) 7 and a first mass analysis magnet (A) connected to the downstream side of the ion source (IS) 7.
M) 8 and a quadrupole magnet (Q) connected via a revolver type multi-RFQ ion accelerator (RFQ) 9 of the present invention.
M) 10, a second mass analysis magnet (AM) 11 connected to the downstream side of the quadrupole magnet (QM) 10, and an end connected to the downstream side of the second mass analysis magnet (AM) 11. Station 12 and the ion source (I
One of the required ions is taken out of S) 7, accelerated by the revolver type multi-RFQ ion accelerator (RFQ) 9 of the present invention, and sent to the end station 12.

As shown in FIGS. 1 and 2, the revolver type multi-RFQ ion accelerator 9 has a rotary shaft 14 supported at the center of a vacuum chamber 13 having a cylindrical shape, and the periphery of the rotary shaft 14. A base 15 having a quadrangular cross section and formed of a conductive material is provided to surround the rotary shaft 14 so as to be rotatable integrally with the rotary shaft 14.

Further, on the four side surfaces of the base 15, along the length direction thereof, a first ion accelerator 16, a second ion accelerator 17, a third ion accelerator 18, and a fourth ion accelerator are respectively provided. Four RFQ ion accelerators, such as 19, are provided.

These RFQ ion accelerators 16, 17, 1
As described above, the reference numerals 8 and 19 intersect the pair of rods 6 with the first support 5 that supports the pair of rods 6 that face each other across the passage direction A of the particles on the base 15 that serves as the base plate. The second supports 5 that support a pair of rods 6 facing each other in the direction are alternately formed upright at predetermined intervals along the length direction of the base 15. Also, support for each of these four ion accelerators 5
Of the first ion acceleration unit 16 (h ₁ ), the second ion acceleration unit 17 (h ₂ ), the third ion acceleration unit 18 (h ₃ ), and the fourth ion acceleration unit 19 (h ₄ ) is the lowest.

Further, as shown in the drawing, each support 5 of the second ion acceleration unit 17, the third ion acceleration unit 18, and the fourth ion acceleration unit 19 excluding the first ion acceleration unit 16 is a base 15.
Conductive base plates 2 with different heights provided above
The height of the base plates 20, 21, 22 is the lowest in the base plate 20, and the heights of the base plates 21 and 22 increase sequentially. Explaining this height relationship concretely, the height of the base plate 20 is the height obtained by subtracting the height (h ₂ ) of the second ion acceleration unit 17 from the height (h ₁ ) of the first ion acceleration unit 16. The height of the base plate 21 is obtained by subtracting the height (h ₃ ) of the third ion acceleration unit 18 from the height (h ₁ ) of the first ion acceleration unit 16, and the height of the base plate 22. Is the height obtained by subtracting the height (h ₄ ) of the fourth ion accelerator 19 from the height (h ₁ ) of the first ion accelerator 16.

Therefore, the particle paths A of the first ion accelerating section 16, the second ion accelerating section 17, the third ion accelerating section 18, and the fourth ion accelerating section 19 with respect to the rotating shaft 14 are all at the same height. There is. Further, as described above, the current path length of each of the first ion acceleration unit 16, the second ion acceleration unit 17, the third ion acceleration unit 18, and the fourth ion acceleration unit 19 is the largest in the first ion acceleration unit 16. Since the resonance frequency due to the inductance L is different, the acceleration energy is also longer than the first ion acceleration unit because the second ion acceleration unit 17, the third ion acceleration unit 18, and the fourth ion acceleration unit 19 sequentially become shorter. The intensity gradually increases from 16 to the fourth ion accelerator 19.

Further, as shown in FIG. 2, a rotary drive mechanism 28 for rotating the rotary shaft 14 in steps of 90 ° is provided at the end of the rotary shaft 14 for the first ion acceleration. The particle passing position A of any one of the portion 16, the second ion accelerating portion 17, the third ion accelerating portion 18, and the fourth ion accelerating portion 19 is located at the ion incident portion 23 formed in the vacuum chamber 13. It is designed to control rotation. The rotary drive mechanism 28 may be configured to automatically drive and control using a drive motor such as a step motor, or may be manually driven arbitrarily.

1, 24 and 25 are tuners for finely adjusting the resonance frequency, a coupler for supplying high-frequency power, and 26 is an exhaust pipe for evacuating the inside of the vacuum chamber 13, and FIG. The middle 27 is an ion emitting portion for emitting accelerated ions to the quadrupole magnet 10 side.

Next, the operation of this embodiment will be described.

As shown in FIG. 2, the ions generated by the ion source (IS) 7 are mass-analyzed by the first mass analysis magnet (AM) 8 to derive only ions having a desired mass, and the revolver type of the present invention is used. The multi-RFQ ion accelerator 9 is made to enter the vacuum chamber 13 from an entrance portion 23 formed in the vacuum chamber 13. Then, the ions are positioned in the ion incidence unit 23, for example, are accelerated by receiving predetermined acceleration energy by the first ion acceleration unit 16 and are emitted from the ion emission unit 27, and are also quadrupole magnets (QM).
The second mass analysis magnet (AM) 1
Only ions of desired energy and mass are selectively extracted at 1 and then injected into a target (not shown) at the end station 12.

At this time, the acceleration energy of the ions accelerated by the revolver type multi-RFQ ion accelerator 9 is determined by the resonance frequency specific to the first ion accelerator 16. That is, the resonance frequency f at this RFQ
Is expressed as f∝1 / 2π (LC) ^1/2 (1). Here, C is the capacitance between the rods, L is the inductance determined by the base 15 or base plates 20-22, and the height H from the upper surface of the base 15 or base plates 20-22 to the beam A position is It depends on twice the sum of the intervals of the supports 5 (current path length). Therefore, if the height of the support 5 is different, the inductance L and thus the resonance frequency f are different, and one type of ion can be accelerated with desired energy.

Considering, for example, the first ion accelerating unit 16 using a support having the highest height with respect to the base 15, the second ion accelerating unit 17 has the same distance between the supports. However, the current path length is equal to the height of the base plate × 2, and the first ion acceleration unit 16
Since it is shorter, the inductance L also becomes smaller, and if this is applied to equation (1), its resonance frequency will increase. Therefore, the acceleration energy of the second ion acceleration unit 17 is also large in the first ion acceleration unit 16. Further, in the third ion accelerating section 18, as described above, the height of the support is lower than that of the second ion accelerating section 17 as well as the first ion accelerating section 16, so that the current The path length is short, the inductance L is small, and the resonance frequency is even higher. Also,
Further, since the support height of the fourth ion acceleration unit 19 is the lowest among the four ion acceleration units, the current path length is the shortest, the inductance L is also the smallest, and its resonance frequency is four. It is the highest among the ion accelerators.

Therefore, by rotating the rotary shaft 14 by the rotary drive mechanism 28, any one of these four ion accelerating units 16, 17, 18, and 19 can be arbitrarily selected, and this makes it easy to obtain a desired one. Acceleration energy can be obtained. Further, as described above, although the four ion accelerating units 16, 17, 18, 19 have different heights of their supports, the remaining ion accelerating units 17, 18, 19 excluding the ion accelerating unit 16 are different. In that case, the base plates 20 and 2 having different heights are used.
Since the heights of the beam passages A with respect to the rotating shaft 14 are all the same by interposing the first and second beams 1 and 22, the beam entrance portion 2 formed in the vacuum chamber 13 is formed.
3 and the beam emitting part 27 are sufficient at one place.

As described above, according to the present invention, the support, that is, the plurality of RFQ ion accelerating portions having different inductances L are radially provided around the rotation axis and centered around the rotation axis, and are rotatably accommodated in the vacuum chamber. By doing so, an ion beam with a large amount of energy can be easily obtained. Also, by simply rotating the rotary shaft,
The desired RFQ ion accelerator can be easily changed.

In this embodiment, the rotation shaft 14 is described with four RFQ ion accelerators having different resonance frequencies. However, the present invention is not limited to this, and the RFQ ions provided on the rotation shaft 14 are not limited to this. It goes without saying that the number of accelerators may be increased or decreased as needed, such as four or more, or conversely two or three. Further, as a modified example of the present invention, the base plates 20, 21, 22 are eliminated, and the heights of the RFQ ion accelerators are different from each other. It is also conceivable to form the beam emitting portion 27 so as to face the radial direction of the vacuum chamber 13.

[0025]

In summary, according to the present invention, it is possible to easily change to a desired RFQ ion accelerating portion only by rotationally driving the rotating shaft, and thus it is possible to easily obtain an ion beam of many energies. The workability is greatly improved. Also, since only one vacuum chamber is required, the overall size can be reduced, and in addition, only one coupler, monitor loop, vacuum exhaust device, etc. are required, resulting in a significant cost reduction. Have the effect.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a partially cutaway side view showing an embodiment of the present invention.

FIG. 3 is a sectional view showing an example of a conventional RFQ ion accelerator.

FIG. 4 is a perspective view showing an ion acceleration unit of a conventional RFQ ion accelerator.

[Explanation of symbols]

 5 Support 6 Rod 13 Vacuum Chamber 14 Rotating Shaft 15 Base 16, 17, 18, 19 RFQ Ion Accelerator A Particle (Beam) Passage

Claims (1)

[Claims] 1. A first support for supporting a pair of rods facing each other across a passage of particles on a base, and a second support for supporting a pair of rods facing each other in a direction intersecting with the pair of rods. A plurality of RFQ ion accelerating parts, which are alternately erected at predetermined intervals, are formed with different heights of the supports, and the plurality of RFQ ion accelerating parts are extended in the passage direction of the particles. A revolver-type multi-RFQ ion accelerator characterized in that the revolver-type multi-RFQ ion accelerator is radially provided around the rotation axis and is rotatably housed in a vacuum chamber.