JP2858776B2 - Beam irradiation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved beam irradiation apparatus for irradiating an ion beam, a neutral particle beam, or an electron beam to a wide area.

(Prior Art) As a method of irradiating a long object with an ion beam, a neutral particle beam, or an electron beam, (1) As shown in FIG. After the charged particles 2 are accelerated by an accelerating electrode 4 having a single electrode hole 3, the beam 5 is deflected by a magnetic field or a deflecting electrode 6 to sweep a wide area, and (2) As shown in FIG. A porous acceleration electrode 9 having a plurality of electrode holes 8
There is a method of extracting a beam 5 from each hole by using a porous electrode (hereinafter, simply referred to as a porous electrode) and obtaining a large-area beam as an aggregate thereof. When a large irradiation intensity is required, the latter method is used. However, a problem in this case is that the beams 5 from the respective holes do not go straight, but diverge spatially. The beam as an aggregate of them may have a spatial distribution 7 as shown in FIG. 2b. That is, there is a problem that the irradiation intensity at the central portion of the collective beam is large and the irradiation intensity decreases toward the periphery. In order to solve this problem, conventionally, as shown in FIG. 3a, some holes at the center of the porous electrode 9 are closed with a closing plate 10 to lower the beam intensity at the center, thereby reducing the spatial intensity. There is a method for obtaining a uniform beam distribution 7. However, this method has a drawback that the beam intensity is reduced by an amount corresponding to closing the hole, and the efficiency of the irradiation device is reduced.

(Problems to be Solved by the Invention) The present invention is intended to solve such problems and disadvantages, and even when a large-area beam is generated using a porous electrode, a spatially uniform beam is generated. The purpose of the present invention is to prevent a reduction in efficiency as in an irradiation device caused by generating a beam and closing an electrode hole.

(Means for Solving the Problems) In order to solve the above problems, in the beam irradiation apparatus of the present invention, the position of the hole at the center of one or more of the plurality of porous electrodes is changed. It is displaced relative to the position of the corresponding hole in the electrode. As a result, in the device of the present invention, a spatially uniform beam can be generated without lowering the irradiation efficiency. The number and position of holes to be displaced (that is, the range of holes in the center to be displaced) and the magnitude of the displacement are appropriately selected according to the output of the apparatus, the type of beam, and the like.

Example A specific example of the present invention will be described with reference to FIGS. 4a, 4b, and 5. FIG. FIG. 4a shows an apparatus for irradiating an ion beam. The ions 12 generated by the plasma source 11 are accelerated by the porous electrode 9. The porous electrode 9 is composed of three electrodes: a plasma electrode 13, a negative electrode 14, and a ground electrode 15. A positive acceleration voltage from an acceleration voltage source 16 is applied to the plasma electrode 13, and a deceleration voltage source is applied to the negative electrode 14. The ion beam is accelerated by applying a negative deceleration voltage from 17. At this time, as shown in FIG. 5, when the hole of the negative electrode 14 is displaced with respect to the holes of the other two electrodes with respect to the hole 18 at the center of the electrode, the beam 5 becomes negative by the action of the electric field lens. It is deflected in the direction opposite to the direction of displacement of the electrode hole. Thereby, the beam (19 in FIG. 4) from the central hole 18 can be deflected outward. Therefore, a uniform beam distribution can be obtained as shown in FIG. 4b.

(Effect of the Invention) As described above, by appropriately selecting the number, position, and magnitude of displacement of the holes to be displaced according to the present invention, a uniform beam distribution over a wide area even when a porous electrode is used. Can be obtained. Further, since the hole of the electrode is not blocked unlike the conventional beam irradiation device using the porous electrode, the beam intensity does not decrease and the efficiency of the irradiation device does not decrease.

[Brief description of the drawings]

1a is a schematic cross-sectional view of a single-hole beam irradiation device, FIG. 1b is a graph showing a beam distribution in the device of FIG. 1a, and FIG. 2a is a beam irradiation device using a porous electrode. FIG. 2b is a schematic diagram showing a beam distribution in the apparatus of FIG. 2a, and FIG. 3a is a schematic sectional view of a conventional beam irradiation apparatus in which the beam distribution from a porous electrode is improved. FIG. 3b is a graph showing a beam distribution in the apparatus of FIG. 3a, FIG. 4a is a schematic sectional view of an ion beam irradiation apparatus of the present invention, and FIG. 4b is a graph showing a beam distribution in the apparatus of FIG. 4a. FIG. 5 is a partial sectional view showing a cross section of one hole and a beam deflection of the porous electrode of FIG. 4a. In the figure, 1 ... a particle source, 2 ... a charged particle 3 ... a single electrode hole, 4 ... an acceleration electrode 5 ... a beam, 6 ... a deflection electrode 7 ... a beam distribution, 8 ... a plurality of electrode holes 9: Perforated electrode, 10: Closing plate 11: Plasma source, 12: Ion 13: Plasma electrode, 14: Negative electrode 15: Ground electrode, 16: Acceleration voltage source 17: Deceleration voltage Source 18 central electrode hole 19 deflected beam from central hole

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H01J 27/00-27/26 H01J 37/08 H01J 37/06 H01J 37/04

Claims (1)

(57) [Claims] 1. A beam irradiation apparatus for accelerating ions or electrons by using a plurality of electrodes having a plurality of holes and irradiating an ion beam, a neutral particle beam, or an electron beam to a large area. By displacing the position of the center hole in one or more of the electrodes with respect to the position of the corresponding hole in the other electrode,
A beam irradiation device for deflecting a beam from a hole at the center of an electrode to the outside.