JPH06162975A - Charged particle irradiation apparatus and beam sensor - Google Patents

Abstract

PURPOSE:To irradiate an ion beam on a sample correctly and uniformly at a low cost by using a beam sensor on which a central metal pipe and a plurality of metal conductors spaced in equal distances from the central metal pipe are provided for aligning the center of the sample to the position of the beam sensor. CONSTITUTION:A beam sensor 2 and a sample hold member 3 are disposed adjacent to each other in a longitudinal window part 1A on a sample holder 1. An ion beam is irradiated on the beam sensor 2 and adjusted so that the distribution of the ion beam becomes uniform. Thereafter, the sample holder 1 is moved in the direction of an arrow, the sample hold member 3 is moved to the position of the beam sensor 2 to align its center to that of the beam sensor 2 and the ion beam is irradiated on the sample. The beam sensor 2 of the abovementioned charged particles, irradiation apparatus has a central metal pipe 2C0 having very small diameter and a plurality of metal conductors 2C1-2C2 each having a very small diameter and spaced at equal distances from the central pipe in uniform distance from there, which are inserted and fixed into the through hole of an electric insulating base member 2B in an envelope 2A, and an electric insulating sheet 2D and a conductive aperture member 2E are placed on the top of the envelope.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle irradiation apparatus capable of irradiating a sample such as a metal thin film with an ion beam or both an ion beam and an electron beam, and a beam sensor used therefor.

2. Description of the Related Art For example, various gas ions are injected from an external ion source into a thin film of a metal material, a semiconductor material or the like to analyze lattice defects thereof, or to a sample which is a wall material of a fusion reactor, For example, an electron microscope is also used for implanting He ions and performing various analyzes. In addition, it is possible to perform microscope observation while irradiating the sample inside the microscope with the ion beam accelerated by the accelerator, and it is possible to directly observe changes in the lattice behavior of the material by irradiation of ions, so The electron microscope is also very effective in measuring microscopic phenomena that control the macroscopic phenomena of. In this case, it is preferable to irradiate the entire surface of the sample with the ion beam substantially uniformly. As an example of a conventional electron microscope used for performing such an analysis, there is disclosed in Japanese Patent Laid-Open No. Sho 62-62.
No. 31930 and Japanese Patent Laid-Open No. 120744/1989. In Japanese Laid-Open Patent Publication No. 62-31930, a sample is irradiated with an ion beam that has passed through the hollow portion of a hollow cylindrical objective lens of an accelerator-coupled transmission electron microscope. The ion beam current applied to these electrodes is monitored by three or more electrodes that are installed at equal intervals on the surface of the objective lens so as to surround the hollow part of the objective lens, and make sure that the current value at each electrode is almost equal. It is to adjust the beam position. At the end of this adjustment, the center of the ion beam is irradiated to the center of the hollow portion, and as a result, the ion beam is irradiated almost uniformly on the entire surface of the sample. Furthermore, the position of the ion beam can be adjusted by importing the monitored current value into a computer such as a microcomputer and giving a command from the computer to the deflector based on the increase or decrease in the current value. As described above, in the conventional charged particle irradiation apparatus, three or more electrodes installed at equal intervals on the wall surface of the objective lens so as to surround the hollow portion can generate an ion current other than the hollow portion, that is, the ion current not irradiated to the sample. It monitors and adjusts the beam position so that the ion beam current value at each electrode becomes equal. The ion beam current applied to the sample cannot be measured, and at the same time, the ion beam irradiation is about 2φ. Irradiation to a wide area other than the target of No. 2 causes ion sputtering and stains inside the electron microscope, which is not a preferable method. If possible, it is necessary not to irradiate ions outside the intended sample range. In order to solve such a problem, in Japanese Patent Laid-Open No. 120744/1989, the ion beam introduced from the ion beam irradiation device into the housing of the electron microscope device is reduced to one minute provided on the sample holder supporting the sample. Since the ion beam current is detected by irradiating the sample through the small holes opened at the bottom of the micro Faraday cup, the amount of ion beam current applied to the sample can be accurately detected. Moreover, in order to detect the distribution state of the ion beam irradiated on the sample, the position of a single micro Faraday cup was moved to various positions.

However, a Faraday cup having an aperture of the same size as the sample of the conventional example is suitable for detecting the total value of the ion beam irradiated on the entire sample at once. However, it is not suitable for detecting the distribution state of the ion beam irradiated on the entire sample in a short time. In addition, when the position of a single micro Faraday cup is moved to detect the distribution of the ion beam that irradiates the sample, it takes a considerable amount of time to detect the overall distribution. There are the following problems in confirming the distribution state of the ion beam. During the change of the state of the sample due to the irradiation of the ion beam, the ion beam is removed from the sample for a long time in order to observe the state of distribution of the ion beam. It changes state changes such as coalescence, disappearance, or temperature change due to ion beam irradiation, resulting in discontinuity. In addition, the conventional ion beam sensor used a micro Faraday cup, etc., so the structure had to be relatively complicated.
Therefore, the present invention provides a very inexpensive beam sensor with a simple structure, detects the distribution state of the ion beam current actually applied to the sample by such a beam sensor in a short time, and also provides a sample in an electron microscope. The purpose is to align the center of the ion beam with the center position of.

According to the present invention, a sample placed at a sample position and an ion beam irradiation surface of the sample are arranged adjacent to the sample position so as to be located in a region having substantially the same area. And a sample holder having a beam sensor composed of a small diameter metal pipe and a plurality of small diameter metal conductors provided around the small diameter metal pipe. By irradiating the conductor, the distribution of the ion beam current in the minute region of the surface area corresponding to the ion irradiation surface of the sample is detected, and the distribution of the ion beam current detected by these small diameter metal conductors becomes almost equal. As described above, the direction of the ion beam is adjusted by adjusting one or more voltages of the power source for the prism and the power source for the analysis magnet, and the power source for the ion source magnet, the upstream lens power source and the downstream lens power source are adjusted. Adjust the spread of the ion beam by adjusting one or both of the voltage's power supply, in which uniformly irradiates the ion beam to the sample. Furthermore, a small-diameter metal pipe having a beam passage small hole in it, a plurality of small-diameter metal conductors arranged around the small-diameter metal pipe through an insulating material, and a sleeve and an enclosure for supporting them. It is a beam sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a part of a sample holder 1 made of a metal material. A beam sensor 2 and a sample holding member 3 are provided in a longitudinal window 1A provided along the axis of the sample holder 1.
And are mounted next to each other by pins or screws. As shown in FIG. 2, the beam sensor 2 includes an envelope 2A,
It is composed of an electrically insulating base member 2B, a small diameter metal pipe 2C ₀ located at the center and a plurality of small diameter metal conductors 2C _{1 to} 2C ₄ arranged around it, an insulating sheet member 2D, and an aperture member 2E made of a metal material. . The envelope 2A has a rectangular parallelepiped outer shape made of a metal material, a circular window is opened in the upper part, and the lower part is completely opened. A portion of the side wall of the envelope 2A has an inner diameter substantially equal to the outer diameter of the electrically insulating base member 2B, and the electrically insulating base member 2B is fitted into that portion. The envelope 2A is provided with a pair of mounting holes 2a on the opposing outer walls, and is attached to the window portion of the sample holder 1 by a pin or a screw. The electrically insulating base member 2B is a disk-shaped member made of an electrically insulating material, and has a small-diameter metal pipe 2C ₀ at its center and at positions equidistant from the center and separated from each other by approximately 90 °.
And a plurality of through-holes for mounting of small diameter metal conductor 2C ₁ ~2C _4. The inner diameter of each through hole is a small diameter metal pipe 2C
₀ and substantially equal to the plurality of the outer diameter of the small diameter metal conductor 2C ₁ ~2C _4, small diameter metal pipe 2C ₀ and a plurality of small diameter metallic conductors 2C ₁ ~2C ₄ is fitted into each of these through holes. The small-diameter metal pipe 2C ₀ is made of a metal material such as stainless steel and has an outer diameter considerably smaller than the ion irradiation area of the sample held by the sample holding member 3. For example, when the diameter of the ion irradiation region of the sample is 3 mm, the small diameter metal pipe 2C ₀ has an outer diameter of 0.2 mm, an inner diameter of 0.1 mm, and a length of 2.5 mm. That is, the small-diameter metal pipe 2C ₀ has a diameter of 0.1 for passing the beam.
It has a beam passage Ho with a diameter of mm. Since this small diameter metal pipe 2C ₀ is thin and can be freely bent, a lead wire for drawing out the detected beam current may be soldered separately, but the small diameter metal pipe 2C ₀ is made longer,
This may be bent as desired and the free end side may be used as a leader line. In addition, four fine metal conductors 2C _1, 2C _2,
2C _{3 and} 2C ₄ have an outer diameter of 0.5 mm and a length of 4
It is an insulation-coated copper wire of 00 mm. Since these minute diameter metal conductors 2C _1, 2C _2, 2C _3, 2C ₄ can also be bent freely, their free end side also functions as a lead wire for drawing out a current corresponding to the detected ion. Further, these four fine metal conductors 2C _1, 2C _2, 2C _3, 2C ₄ may be metal pipes such as the fine metal pipe 2C ₀ . Since the ion beam obliquely enters these metal pipes, it is not necessary to strictly close the lower ends.
Then, the small-diameter metal pipe 2C ₀ and the small-diameter metal conductors 2C _{1 to} 2C ₄ are preferably arranged next to the beam sensor 2 by being arranged so that their upper ends are at the same level as the upper surface of the electrically insulating base member 2B. The beam is positioned at the same level as the set sample, and a favorable beam detection can be performed. The above-mentioned embodiment is used when in-situ observation is performed by irradiating a sample in an electron microscope, but it is not necessary to accurately detect the ion irradiation amount, and it is necessary to uniformly irradiate the sample. If you want to detect a typical ion distribution,
The minute passage Ho for passing the electron beam is unnecessary. Therefore, it is possible to use an elongated conductor such as a copper wire which is the same for all five wires. The insulating sheet member 2D is a thin electric insulating sheet having a size substantially equal to the surface area of the upper surface of the electric insulating base member 2B, and is a position where the small diameter metal pipe 2C ₀ and the small diameter metal conductors 2C _{1 to} 2C ₄ are arranged. Has holes 2D ₁ approximately equal to their inner diameters. The insulating sheet member 2D is placed on the electrically insulating base member 2B, and the aperture member 2E, the small diameter metal pipe 2C ₀ , and the small diameter metal conductors 2C _{1 to} 2C _{4 are} placed thereon.
Provide electrical insulation between. The aperture member 2E is a thin circular plate made of a metal material, and this is also a part of the insulating sheet member 2D at the positions corresponding to the positions where the small diameter metal pipe 2C ₀ and the small diameter metal conductors 2C _{1 to} 2C ₄ are arranged. Hole 2
It has a hole 2E ₁ with a diameter slightly smaller than D ₁ , and this hole is
The hole diameter has an accurate diameter because it determines the current density. The aperture member 2E is connected to a fixed potential. Incidentally, in the above embodiment, the small diameter metal conductors 2C _{1 to} 2C are used.
The cross sections of ₄ are not limited to circular shapes, but may be of any shape. Next, an embodiment of the charged particle irradiation apparatus of the present invention will be described with reference to FIG.
Is an ion source magnet, 11 is a variable DC power supply for the ion source magnet, 12 is an upstream lens for focusing the ion beam, 13 is a variable DC power supply for the upstream lens, 14 is an analysis magnet for analyzing and deflecting undesired ions, 15 Is a variable DC power source for the analysis magnet, 16 is a downstream lens for refocusing the ion beam, 17 is a variable DC power source for the downstream lens, 18 is a prism device for electrostatically deflecting the ion beam, and 19 is a variable device for the prism device. DC power supply,
These have the same configurations as conventional ones. Control / display mechanism 2
0 is a variable DC power supply 11, 1 according to the size of the ion beam detected by the small diameter metal conductors 2C _{1 to} 2C ₄ described above.
It controls one or more of 3, 15, 17, and 19.
This is due to the difference in the magnitude of the ion detection signals detected by the pair of two small-diameter metal conductors 2C ₁ and 2C _2, 2C ₃ and 2C ₄ facing each other with the small-diameter metal pipe 2C ₀ located in the center as the center. One or more voltages of the variable DC power supplies 11 and 13 and 17, and the variable DC power supplies 15 and 19 are controlled so that each becomes approximately zero. Next, operations and operations will be described with reference to these drawings. As shown in FIG. 3, when the sample in the electron microscope apparatus is subjected to in-situ observation while irradiating an ion beam to observe the behavior of the sample such as a crystal lattice, first, the sample holder 1 shown in FIG.
Is adjusted so that the electron beam from the electron gun (not shown) passes through the minute passageway Ho of the minute diameter metal pipe 2C ₀ located at the center of the beam sensor 2. This alignment is performed by adjusting the position of the sample holder 1 so that the shadow of the beam passage Ho is in the center of the image observation fluorescent plate (not shown) of the electron microscope. Next, the sample holder 1 is fixed at that position, and ion beam irradiation is performed. The control / display mechanism 20 has a difference in magnitude of ion detection signals detected by the pair of small-diameter metal conductors 2C ₁ and 2C _2, 2C ₃ and 2C ₄ facing each other with the small-diameter metal pipe 2C ₀ as the center. Adjust the voltage of the variable DC power supplies (or variable DC power supplies for ion source magnets) 11 and 13 and 17 for the upstream lens and the downstream lens so that it becomes almost zero to adjust the spread of the ion beam and also for the prism. And variable DC power supply for analysis magnet 1
The direction of the ion beam is adjusted by controlling one or more voltages of 9 and 15, and the ion beam distribution uniform position where the distributions of the ion beam currents are almost equal is obtained. Next, the sample holder 1 is moved in the direction of the arrow by the distance X between the center of the beam passage Ho of the small diameter metal pipe 2C _{0 and} the center of the sample holding member 3, that is, the center of the sample 4, and the ion beam distribution uniform position is obtained. Set to. Alternatively, the position of the through hole (not shown) of the sample may be located at the center of the fluorescent plate by observing the image of the sample at a low magnification. As a result, the center of the sample 4 is the beam passage Ho of the small diameter metal pipe 2C _0.
This means that the sample 4 has been moved in parallel to the position of, and the entire surface of the sample 4 at the axis center of the electron microscope is irradiated with the ion beam substantially uniformly. In this way, the sample can be irradiated with an ion beam current having a substantially uniform distribution in a very short time. Further, the same operation as described above may be performed on the sample in the ion beam irradiation apparatus. In the case of manually without them automatically, small diameter metal pipe 2C and small diameter metal conductor 2C ₁ meter shown ～2C ₄ beam current detection values respectively, or a display, indicated by these One or more volumes of variable DC power supplies 11 and 13 and 17 for upstream lens and downstream lens or ion source magnet, and variable DC power supplies 19 and 15 for prism and analysis magnet while observing the beam current detection value. Should be adjusted. Further, the positions of the beam sensor 2 and the sample holding member 3 may be replaced with each other. In this case, after obtaining the ion beam distribution uniform position, the sample holder is moved by the distance X in the direction opposite to the arrow. . In the embodiment, the small-diameter metal pipe 2C ₀ and the small-diameter metal conductors 2C _{1 to} 2C ₄ are used as the beam sensor 2, but these are taken into consideration in consideration of their mounting space, the required detection accuracy of the ion beam distribution state, and the like. Although the number of adopted, the interval, etc. may be determined, the fine metal pipe 2C ₀ and two or more fine metal conductors are required. In particular, when the detection center is not required, as in the case of being used in the ion beam irradiation apparatus, the small diameter metal pipe 2C ₀ can be omitted.
The same applies not only to the combination of the ion beam irradiation device and the electron microscope as in the above-described embodiment, but also to the charged particle irradiation device in which the ion beam irradiation device and the laser beam irradiation device are combined. In this case, adjustment is performed so that the shadow of the beam passage Ho caused by the laser beam is located at the center of the image observation fluorescent plate. Next, with reference to FIG. 4, another embodiment of the beam sensor 2 which is simpler to manufacture and less expensive will be described. The envelope 2A has a rectangular parallelepiped outer shape made of a metal material, has a circular window at the top, and has a tapered recess 2A1 so that the beam can be easily irradiated. The bottom portion 2A2 of the recess 2A1 has a through hole 2A3 of a square shape when viewed from above, and has a small diameter metal pipe 2C ₀ and small diameter metal conductors 2C ₁ to 2C 2.
The bundle of C ₄ is fitted into the through hole 2A3 and extends downward. The small-diameter metal pipe 2C ₀ is preferably formed with a thin electric insulation coating on its surface, but since the electric insulation coating is broken at the upper end of the pipe,
To prevent a short circuit between the envelope 2A and one of small diameter metal conductor 2C ₁ ~2C _4, a portion including the upper end portion with an electrically insulating material, 2F, such as Teflon is coated. Likewise small-diameter metal conductor 2C ₁ ~2C ₄ also, since preferably is a thin electrically insulating film on its surface is formed at its upper end is electrically insulating coating is destroyed at the time of cutting, the envelope 2
And to prevent a short circuit between one of A and small diameter metal conductor 2C ₁ ~2C _4, in order to bundle them, a portion including the upper end portion with an electrically insulating sheet 2G such as Teflon is wound. In this way, centering on the small diameter metal pipe 2C ₀ , the small diameter metal conductors 2C _{1 to} 2C _{4 are} contacted around the small diameter metal pipe 2C ₀ through the electric insulating material 2F, and the electric insulating sheet 2
Since the one bundled with G is fitted into the through hole 2A3 of the envelope 2A, the detection accuracy is lower than that of the beam sensor of the above-mentioned embodiment, but a very inexpensive and small beam sensor can be obtained. . Although not shown, the fine metal pipe 2C ₀ is brazed with a fine lead wire by silver brazing or the like, and the fine metal conductors 2C _{1 to} 2C ₄ are also attached.
Since it has a thickness that can be easily bent, it also serves as a thin drawing wire. Also in this embodiment, the minute metal conductors 2C _{1 to} 2C ₄ may be minute metal pipes. Next, with reference to FIG. 5, another embodiment of the beam sensor 2 which is easy and inexpensive to manufacture with the same configuration as the above-mentioned embodiment will be described. The envelope 2A has a rectangular parallelepiped outer shape made of an insulating material, a circular window is opened in the upper part, and a tapered recess 2 is formed so that the beam can be easily irradiated.
Equipped with A1. The bottom portion 2A2 of the recess 2A1 is provided with a minute passageway Ho for passing an electron beam in the center thereof, and the wall surface forming the minute passageway Ho is formed of a metal such as aluminum by sputtering or plating. The film 2C ₀ 'is formed. The metal film 2C ₀ ′ on the wall surface of the minute passage Ho plays the same role as the minute diameter metal pipe 2C _{0 of the} above-mentioned embodiment. Further, on the bottom portion 2A2 of the recess 2A1, four metal films 2C ₁ ′ to 2C ₄ ′ having the same area around the minute passage Ho are formed by depositing a metal material such as aluminum or sputtering. These are the small-diameter metal conductors 2C of the above embodiment.
It plays the same role as the _{1 ~2C 4.} These metal films 2C ₀ '~
2C ₄ 'includes lead wires L ₀ , which are thin metal wires,
L ₁ , L ₂ , L ₃ , and L ₄ are brazed by silver solder or the like. From lead line L _0, to obtain a detection signal corresponding to the beam current passing through the small passage Ho, also ion content is from lead line L ₁ ~L ₄ irradiated to the metal film 2C ₀ '~2C _4' A detection signal corresponding to each is obtained. The metal films 2C ₀ ′ to 2C ₄ ′ are formed on the bottom 2A2 of the recess 2A1.
Alternatively, a metal film may be formed on the entire surface in advance, and then etching may be performed according to a predetermined pattern. Although the envelope 2A is made of an insulating material, a conductive material such as a metal may be used. In this case, an insulating film such as a polyimide resin is formed on the entire bottom portion 2A2 of the recess 2A1. The above-mentioned metal films 2C ₀ ′ to 2C ₄ ′ may be formed on it.

As described above, according to the present invention, the following effects can be achieved. 1. A beam sensor that is easy to manufacture, inexpensive, and small can be obtained. 2. It is possible to instantaneously detect the distribution state of the ion beam current that is very close to the ion beam actually irradiated on the sample in the charged particle irradiation apparatus. 3. The sample can be irradiated with an ion beam having a substantially uniform distribution. 4. The center of the ion beam can be aligned with the center position of the sample in the electron microscope apparatus. 5. Therefore, since in-situ observation can be performed while irradiating the sample with an ion beam having a substantially uniform distribution, various analyzes and observations of metal materials and semiconductor materials can be performed accurately. 6. Since the distribution state in the microscopic region of the sample becomes clear,
By focusing and irradiating the ion beam, the irradiated and unirradiated parts of the sample are clarified, which divides a valuable sample into two or more parts,
Irradiation experiments can be performed under different conditions.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a sample holder used in a charged particle irradiation apparatus according to the present invention.

FIG. 2 is a diagram showing an embodiment of a beam sensor according to the present invention.

FIG. 3 is a diagram showing an embodiment of a charged particle irradiation apparatus according to the present invention.

FIG. 4 is a diagram showing an embodiment of another beam sensor according to the present invention.

FIG. 5 is a diagram showing an embodiment of another beam sensor according to the present invention.

[Explanation of symbols]

1 ... Sample holder 2 ... Beam sensor 2A ... Enclosure 2B ... Electrically insulating base member 2C ₀ ... Small diameter metal pipe 2C _{1 to} 2C ₄ ... Small diameter metal conductor 2D ・ ・ ・ Electrically insulating sheet member 2E ・ ・ ・ Aperture member 3 ・ ・ ・ ・ Sample holding member 4 ・ ・ ・ ・ Sample 10 ・ ・ ・ ・ Ion source magnet 11 ・ ・ ・ ・ ・ ・ Power source for ion source magnet 12 ・ ・ ・・ Upstream lens 13 ・ ・ ・ ・ Power supply for upstream lens 14 ・ ・ ・ ・ ・ ・ Power supply for analysis magnet 15 ・ ・ ・ ・ Power supply for analysis magnet 16 ・ ・ ・ ・ Downstream lens 17 ・ ・ ・ ・ ・ ・ Power supply for downstream lens 18 ・ ・ ・ ・ ・ ・ Prism Device 19 ・ ・ ・ ・ Power source for prism device 20 ・ ・ ・ ・ ・ ・ Control / display mechanism Ho ・ ・ ・ ・ Micro passage 2C ₀ 'to 2C ₄ ' ... Metal film L _{0 to} L ₄ ... line

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Claims (9)

[Claims] 1. A sample placed at a sample position, and a plurality of small-diameter metal conductors arranged adjacent to the sample position so as to be located in a region having substantially the same area as the ion beam irradiation surface of the sample. A sample holder having a beam sensor, and irradiating the plurality of minute diameter metal conductors with an ion beam to be irradiated onto the sample, so that a small area of a surface area corresponding to the ion irradiation surface area of the sample is provided. A charged particle irradiation apparatus characterized in that the distribution of the ion beam current can be detected. 2. A sample placed at a sample position, a small-diameter metal pipe arranged next to the sample position so as to be located in a region having substantially the same area as the ion beam irradiation surface of the sample, and A sample holder having a beam sensor composed of a plurality of small-diameter metal conductors located around the sample holder is provided in the charged particle irradiation apparatus, and the ion beam irradiated to the sample is first irradiated to the plurality of small-diameter metal conductors. Detecting the ion beam distribution uniform position where the distributions of the ion beam currents detected by these small-diameter metal conductors are almost equal, and then moving the sample holder to set the sample to the ion beam distribution uniform position. A charged particle irradiation apparatus, which irradiates an ion beam on a surface of a charged particle. 3. A sample placed at a sample position, a micro-diameter metal pipe having a single beam passage so as to be located in a region having substantially the same area as the ion beam irradiation surface of the sample, and the micro-diameter metal pipe. A beam sensor composed of a plurality of small-diameter metal conductors that are equidistant from each other at the center and a beam introduced into a charged particle irradiation apparatus equipped with a sample holder arranged next to the sample position The center position is determined by passing through the beam passage of the small-diameter metal pipe, the sample holder is set at the center position, and in this state, the ion beam is irradiated to the plurality of small-diameter metal conductors for detection, Adjust the voltage of one or more of the power source for the prism, the power source for the analysis magnet, and the power source for the ion source magnet so that the distribution of the ion beam current detected by the small-diameter metal conductor is almost equal. A charged particle irradiation apparatus characterized by adjusting the beam direction and adjusting the voltage of one or both of an upstream lens power supply and a downstream lens power supply to adjust the divergence of an ion beam. 4. An electrically insulating base member having a through hole provided in the center, two or more other through holes equidistant from the center, a through hole provided in the center, and the two or more. A small-diameter metal conductor provided through each of the through holes, an electric insulating sheet placed on the upper end surfaces of the small-diameter metal pipe and the small-diameter metal conductor, and an upper surface of the electric insulating sheet. A beam sensor, comprising: a small diameter metal pipe; and a conductive aperture member having a plurality of apertures at locations corresponding to the small diameter metal conductors. 5. A small-diameter metal pipe covered with an insulating material having a beam passage, a plurality of small-diameter metal conductors arranged around the small-diameter metal pipe through the insulating coating, and the small-diameter metal pipe. A beam sensor comprising: an envelope that supports the plurality of small-diameter metal conductors. 6. An electrically insulative envelope having a beam passage, a metal film formed on an inner wall forming the beam passage, and the electrically insulative envelope around the beam passage. A beam sensor comprising: a plurality of metal films formed on an ion irradiation surface; and a lead wire connected to each of the metal films. 7. The beam sensor according to claim 1, wherein the fine metal conductor is a fine metal wire. 8. The beam sensor according to claim 1, wherein the fine metal conductor is a fine metal pipe. 9. The beam sensor according to claim 1, wherein the small-diameter metal conductor is a metal film.