JPH10134746A - Optical axis adjustment method for focused ion beam and focused ion beam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical axis alignment method and a focused ion beam device of a focused ion beam facilitating axis alignment work during ion source replacement of a focused ion beam device or the like. SOLUTION: This device has an ion source part 3 consisting of an ion source 1 generating an ion beam and a lead electrode 2, a first aperture 5 passing a center part having high current density of the ion beam and measuring that current, a charged particle optical system 9 including a second aperture and an object lens 8, a deflection electrode 16 for scanning the focused ion beam, and a secondary charged particle detector for detecting a secondary charged particle generated by irradiating the focused particle with a sample. A quantity of the secondary charged particle to be detected by the secondary charged particle detector is monitored while the ion source 1 is moved in a direction orthogonal to an optical axis of the ion beam, and a position of the ion source 1 is adjusted so that a quantity of the secondary charged particle is extremely large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of adjusting the optical axis of an ion beam in a focused ion beam device and a focused ion beam device.

[0002]

2. Description of the Related Art Conventionally, for example, a document “Submicron processing by a focused ion beam (SSD81-76)”
(See IEICE, December 21, 1981) An ion beam emitted from a liquid metal ion source such as gallium is squeezed with a fixed iris, and the beam current and diameter are obtained over a wide range. For this purpose, an aperture having a plurality of different apertures, which can be selected arbitrarily, further narrows the ion beam, focuses it in a spot shape with an objective lens, irradiates it with a raster scan using a scanning electrode, and irradiates the sample surface. A focused ion beam device for performing processing is known. The image display apparatus further includes an image display device that displays a pattern on the surface of the sample based on a planar intensity distribution of secondary charged particles emitted from the surface of the sample irradiated with the ion beam.

In such a focused ion beam apparatus, it is necessary to allow the ion beam to pass through the center of an ion optical system component such as a stop, a lens, and a deflection electrode in order to sufficiently exhibit its performance. ing. For this reason, high-precision processing is performed in the production of each part, and assembling ensures micron-order assembly accuracy, thereby realizing the performance as an apparatus.

[0004] However, the ion source is consumed due to the use of the focused ion beam apparatus and must be replaced as needed. The ion beam generated from the new ion source at the time of replacement always passes through the center of the ion optical system component. do not do. For this reason, its position must be adjusted so that the ion beam passes through the center of the ion optical system component.

A diaphragm having a plurality of different apertures, which can be selected arbitrarily, must be periodically replaced because it is worn or soiled by use of the focused ion beam apparatus. . At the time of such replacement, the center of the new diaphragm and the ion beam are displaced from each other, so that the adjustment must be performed.

[0006]

That is, conventionally, when the ion source is replaced, for example, Japanese Unexamined Patent Publication No. Hei.
As shown in the apparatus described in Japanese Patent Application Laid-Open No. 9-29, an ion source is mounted on an XY stage and the position of the ion source is adjusted by driving the XY stage. However, in this case, the position of the ion source is visually confirmed on a CRT monitor to adjust the positional deviation, and the ion beam generated from the ion source passes through the center of the ion source optical system components. The method that can be judged is not described. As another example, Japanese Utility Model Application Laid-Open No.
As described in Japanese Patent Application Laid-Open Publication No. H10-107, there is an apparatus provided with a second anode portion movably in a horizontal direction and a drive mechanism for driving the second anode portion in a horizontal direction. This is an apparatus for an electron gun, but can also be used for an ion source. However, even in this example, there is no description about how to determine that the beam passes through the center of the optical system component.

For this reason, conventionally, it has been realized by repeatedly performing the operation for adjusting the position of the ion source so as to converge to the target position, and the degree of achievement of the adjustment and the time required for the operation are reduced by the operator. It will depend on your skills. Further, since the parameters relating to the adjustment are not quantified, the adjustment cannot be performed automatically by a computer.

As one solution to such position adjustment, there is a method described in Japanese Patent Application Laid-Open No. 61-88437. In this method, the substance to be ionized stored in the storage section is gradually supplied to a storage section which is kept in a molten state, so that the substance can be used for a long time without changing the position of the ion source. is there. In other words, this method eliminates the need for adjusting the position of the ion source. However,
According to this method, the ion beam and the particles generated secondarily pass through the plurality of transmitted lights and become a noise component because the structure is complicated and there are a plurality of transmission holes having different opening diameters. Therefore, it is difficult to achieve performance such as image quality and resolution required for a focused ion beam device.

On the other hand, the effect of using a plurality of apertures having different aperture diameters is described in the above-mentioned document “Submicron processing by a focused ion beam”. Further, regarding a method of selecting an optimal aperture from different apertures, JP-A-3-16
No. 3741, the center of the aperture is not accurately aligned with the ion beam. Therefore, in the same manner as the position adjustment of the ion source, the operation is repeatedly performed to converge on the target position to realize the position adjustment. Therefore, the degree of achievement of the adjustment and the time required for the operation depend on the skill of the operator. become. Further, since parameters relating to adjustment are not quantified, they cannot be automated and performed by a computer.

In view of such circumstances, the present invention provides a focused ion beam optical axis alignment method and a focused ion beam apparatus which facilitates axis alignment work when exchanging an ion source or a diaphragm of the focused ion beam apparatus. The purpose is to do.

[0011]

According to the present invention, there is provided an ion source section comprising an ion source for generating an ion beam and an extraction electrode, and a first section for passing a central portion of the ion beam having a high current density. Aperture, a condenser lens, a charged particle optical system that includes a second aperture and an objective lens, and the focused ion beam is an ion beam that has passed through the first aperture, and a deflection electrode that scans the focused ion beam; A method of adjusting an optical axis of a focused ion beam device having a secondary charged particle detector for detecting secondary charged particles generated by irradiating a sample with the focused ion beam, wherein the ion source; And the second aperture is detected by the secondary charged particle detector while moving in a direction orthogonal to the optical axis of the ion beam. The amount of the secondary charged particles is monitored, and the position of the ion source and / or the second aperture is adjusted so that the amount of the secondary charged particles or the ion current irradiating the sample surface is maximized. In the method of adjusting the optical axis of the focused ion beam.

Furthermore, an ion source section having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, a condenser lens, a second aperture and an objective Generated by irradiating a sample with the focused ion beam, a charged particle optical system that converts the ion beam that has passed through the first aperture including the lens into a focused ion beam, a deflection electrode that scans the focused ion beam, A secondary charged particle detector for detecting secondary charged particles to be moved, a first XY direction moving means for moving the ion source in a direction orthogonal to an optical axis of the ion beam, and the secondary charged particle detector. First XY-direction movement control means for controlling the first XY-direction movement means using an amount of detected secondary charged particles as an index; A second XY direction moving means capable of moving the second aperture in a direction orthogonal to the optical axis of the ion beam; and the second XY direction moving means using the amount of secondary charged particles detected by the secondary charged particle detector as an index. And a second XY-direction movement control means for controlling the XY-direction movement means.

With the above arrangement, while moving the ion source and / or the second aperture, the amount of the secondary charged particle or the irradiation ion beam current detected by the secondary charged particle detector is maximized. Control movement of the ion source or / and the second aperture. By performing such control, the center of the beam current density of the ion beam generated from the ion source, the center of the through hole of the first aperture, and the center of the through hole of the second aperture coincide.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

[0015]

FIG. 1 is a diagram showing a schematic configuration of a focused ion beam apparatus according to a first embodiment. As shown in FIG. 1, for example, a liquid metal ion source 1 made of Ga or the like and an ion source unit 3 having an extraction electrode 2 are provided with a first XY
The first XY direction moving device 4 is mounted on the direction moving device 4 and is provided so as to be movable in the XY directions which are two directions orthogonal to the axis of the beam generated from the ion source unit 3. On the beam irradiation side of the ion source 3, a first aperture 5 having a first through hole 5a for passing only a central portion of the high-brightness ion beam B1 generated from the ion source 3 with a high current density is provided. Are located. A charged particle optical system 9 including a condenser lens 6, a second aperture 7 and an objective lens 8 is arranged along the beam axis on the beam emission side of the first aperture 5. The high-intensity ion beam B1 generated from the ion source 1 is focused by the charged particle optical system 9 to become a focused ion beam B2.

Here, the second aperture 7 has a plurality of second through holes 7a having different diameters (other through holes are not shown), and can be switched by the through hole switching device 10. Has become. That is, the diameter of the second aperture 7 in which the plurality of through holes 7a having different dimensions are arranged on the beam axis can be changed by the through hole switching device 10. In this example, a plurality of second through holes 7a having different diameters are provided.
The member having the second through hole 7 is slid.
The diameter of a can be changed. However, the diameter of the single second through-hole 7a, such as a pupil or a diaphragm of a camera, may be changed continuously or stepwise. Thus, the configuration of the through-hole switching device 10 is not particularly limited.

The second aperture 7 has a second XY
The direction moving device 11 can move the radial position of each second through hole 7a in the XY directions. A blanking means 14 comprising a blanking electrode 12 and a blanking aperture 13 is provided on the beam emission side of the charged particle optical system 9 to turn on and off the focused ion beam. That is, when the focused ion beam B2 is turned off, a voltage is applied to the blanking electrode 12 to largely deflect the focused ion beam B2 so that the focused ion beam B2 is cut off by the blanking aperture 13. The arrangement of the blanking electrode 12 and the blanking aperture 13 is not limited to this, and may be arranged, for example, above or in the middle of the charged particle system 9.

A deflection electrode 16 for scanning the focused ion beam B2 passing through the blanking aperture 13 to a desired position is arranged on the beam emission side of the blanking aperture 13. The focused ion beam B2 to be scanned and irradiated on a desired position / region of the sample 18 on the sample stage 17 is irradiated.

Above the sample stage 17, a secondary charged particle detector 19 for detecting secondary charged particles emitted from the surface of the sample 18 irradiated with the focused ion beam B2 is arranged. The charged particle detector 19 amplifies the detection signal and obtains the planar intensity distribution of the secondary charged particles. The image control unit 20 generates the planar intensity distribution of the secondary charged particles. Connected to an image display device 21 for displaying a current pattern.

Further, a Faraday cup 15 whose position can be exchanged with the sample stage 17 is provided beside the sample stage 17. The Faraday cup 15 receives the irradiation of the focused ion beam B2 instead of the sample 18, and measures the beam current. The Faraday cup 15 may be provided on the sample stage 17 and at a position that does not overlap with the sample 18.

The extraction electrode 2, blanking electrode 12, and deflection electrode 16 are connected to an extraction power supply 22, a blanking power supply 23, and a deflection power supply 24 for applying desired voltages to the respective electrodes.
Furthermore, while controlling such a focused ion beam device as a whole as a whole, the first XY-direction moving device 4, the through-hole switching device 10, the second XY-direction moving device 11, and the above-described power supplies 22 to 24 And the like are provided with a control unit 25 composed of a computer system capable of individually controlling the operations. That is, the control unit 25 includes first XY-direction movement control means for controlling the movement and position of the first XY-direction movement device 4 for moving the ion source unit 3 in a plane. Control unit 2
Reference numeral 5 denotes a second X that controls the movement and position of the second XY direction moving device 4 that moves the second aperture 7 in a plane.
Y direction movement control means is included.

In such a focused ion beam apparatus, the ion beam B1 extracted from the ion source 3 is focused by the charged particle optical system 9 and scanned by the deflection electrode 16 to irradiate the sample 18 to process the sample 18. It can be performed. Although not shown in this example, a gas irradiation nozzle is provided in the vicinity of the sample 18 and gas is supplied from the gas irradiation nozzle simultaneously with the irradiation of the focused ion beam B2 to locally perform ion beam assisted CVD. A membrane can be made.

When such processing is performed, the setting of the processing position / region and the processing state are performed by image observation on the image display device 21. Although not shown in this example,
For example, the surface of the sample 18 may be illuminated by general illumination, and the sample surface may be simultaneously observed by an optical microscope.

Hereinafter, a method of adjusting the optical axis of such a focused ion beam apparatus will be described. At this time, the workability can be improved by using a sample 18 having a uniform flat surface with no unevenness and a high secondary charged particle yield. First, the optical axis adjustment of the ion source unit 3 will be described. The amount of secondary charged particles detected by the secondary charged particle detector is monitored while moving the ion source unit 3 in the X and Y directions by the first XY direction moving device 4, and the secondary charged particles are The ion source unit 3 is fixed at the point where the amount of P has reached a maximum.

Here, the first XY-direction moving device 4 is not particularly limited as long as it can move the ion source section 3 minutely in at least two directions. For example, the X-direction movement and the Y-direction movement are independent. The operation may be performed by linear actuators. Further, the first XY direction moving device 4 may be a device which can be automatically moved under the control of the control section 25 including the first XY direction moving control means, or may be a device which can be finely moved manually. For example, as a specific example, an apparatus described in JP-A-3-29249 can be mentioned.

In this embodiment, the ion source 3
However, it is obvious that the same effect can be obtained even if only the ion source 1 is moved. In addition, the configuration of the ion source unit 3 is not limited to the configuration including only the ion source 1 and the extraction electrode 2. For example, the ion source unit 3 may include a control electrode for controlling generation of an ion beam in addition to the extraction electrode. . Also in this case, the entire ion source unit 3 may be moved, or only the ion source 1 may be moved, or
Only the ion source 1 and the control electrode may be moved. In the following embodiments, the description will be made assuming that the ion source unit 3 is moved, but the same applies to the following.

Next, the optical axes of the charged particle optical system 9, particularly the second aperture 7, are aligned. In this case, aperture 7
Are moved in the X direction and the Y direction by the second XY direction moving device 10.
While moving in the respective directions, the amount of the secondary charged particles detected by the secondary charged particle detector 19 is measured, and the second aperture 7 is fixed when the amount of the secondary charged particles becomes maximum. The second XY direction movement device 4 can automatically move under the control of the control unit 25 including the second XY direction movement control means.

Each of the optical axis adjustments described above can be adjusted by using the amount of secondary charged particles detected by the secondary charged particle detector as a judgment material. Or, since it is converted into an electric signal such as a voltage value, automatic adjustment is possible by computer control, and the best alignment is always performed quickly and objectively as compared with a method relying on the experience and skill of the operator. There is an advantage that can be. Further, since the optical axis can be aligned using an objective measurement value as an index, there is an advantage that automation by a computer becomes possible.

FIG. 2 shows a case where the ion source 3 is moved in the X-axis direction (a) and the Y-axis direction (b) in the focused ion beam apparatus described above, and is detected by the secondary charged particle detector 19. The result of having measured the change of the amount of secondary charged particles is shown. Then, when a measurement value as shown in FIG. 2 is obtained, a method of automatically performing optical axis alignment by computer processing is not particularly limited. For example, the amount of detected secondary charged particles is −10 from the maximum value. Automation can be performed very easily by a method of determining the middle point of the% point as the center and performing alignment. With this method, it can be driven to the order of several tens of microns.

Although the above-described optical axis adjustment method has been described as an example applied to the focused ion beam apparatus shown in FIG. 1, it is needless to say that the method can be applied to focused ion beam apparatuses having various structures. In order to perform the above-described optical axis adjustment in a case where the first aperture 5 does not substantially exist at the ion beam exit of the ion source, the ion beam is fixed to any one between the charged particle optical system 9 and the deflection electrode 16. An aperture must be provided. Such a fixed aperture has a through hole having a diameter substantially equal to or smaller than the diameter of the focused ion beam, and the center of the through hole needs to be arranged so as to coincide with the optical axis of the charged particle optical system 9. There is.

The above is the description of the ion source 3 and the second
Is set based on the detected amount of secondary charged particles generated from the sample 18 by the focused ion beam irradiation. In addition, the positions of the ion source 3 and the second aperture 7 can be set based on the ion beam current detected by the Faraday cup 15. That is, the amount of the secondary charged particles increases as the irradiation ion beam current increases.

[0032]

As described above, according to the present invention,
Since the optical axis alignment can be realized quickly and objectively by using the amount of the secondary charged particles as an index, it is possible to facilitate the axis alignment work at the time of exchanging the ion source of the focused ion beam apparatus and to perform objective measurement. Since the optical axis can be aligned using the value as an index, there is an effect that automation by a computer can be easily performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a focused ion beam device according to an embodiment of the present invention.

FIG. 2 is a diagram showing test results of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 2 Extraction electrode 3 Ion source part 4 1st XY direction moving device 5 1st aperture 5a Through hole 6 Condenser lens 7 2nd aperture 7a Through hole 8 Objective lens 9 Charged particle optical system 10 Through hole switching device DESCRIPTION OF SYMBOLS 11 2nd XY direction moving apparatus 12 Blanking electrode 13 Blanking aperture 14 Blanking means 15 Faraday cup 16 Deflection electrode 17 Sample stage 18 Sample 19 Secondary charged particle detector 20 Image controller 21 Image display 22 Drawer power supply 23 Blanking power supply 24 Deflection power supply 25 Control unit

Claims (14)

[Claims] 1. An ion source section comprising an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. A charged particle optical system including a second aperture for regulating the outer shape of the ion beam, an objective lens for further restricting the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, and the focusing A method for adjusting the optical axis of a focused ion beam device having a secondary charged particle detector for detecting secondary charged particles generated by irradiating a sample with an ion beam, comprising: Irradiating the focused ion beam onto the sample surface while moving in a direction orthogonal to Measuring the amount of the secondary charged particles by the secondary charged particle detector, and setting the position of the ion source so that the amount of the secondary charged particles is maximized. Axis adjustment method. 2. An ion source having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. A charged particle optical system including a second aperture for regulating the outer shape of the ion beam, and an objective lens that further narrows the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, A method for adjusting the optical axis of a focused ion beam device having a secondary charged particle detector for detecting secondary charged particles generated by irradiation, wherein the second aperture is orthogonal to the optical axis of the ion beam. Irradiating the focused ion beam onto the sample surface while moving in the direction of The amount of particles was measured by the secondary charged particle detector, the optical axis adjusting method of the focused ion beam, wherein the amount of the secondary charged particles to set the position of the ion source so that a maximum. 3. The second aperture is capable of changing the size of a through-hole passing through the ion beam,
3. The method for adjusting the optical axis of a focused ion beam according to claim 2, wherein the position of the second aperture is adjusted with respect to the through holes of each dimension. 4. An ion source section having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. A charged particle optical system including a second aperture for regulating the outer shape of the ion beam, an objective lens for further restricting the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, and the focusing In a method for adjusting the optical axis of a focused ion beam device having a secondary charged particle detector that detects secondary charged particles generated by irradiating a sample with an ion beam, The focused ion beam is irradiated on the sample surface while moving in a direction perpendicular to the optical axis, and emitted by the irradiation. Measuring the amount of secondary charged particles to be performed by the secondary charged particle detector, setting the position of the ion source such that the amount of the secondary charged particles is maximized, and setting the second aperture to Irradiating the focused ion beam to the sample surface while moving in a direction perpendicular to the optical axis of the ion beam; measuring the amount of secondary charged particles generated by the irradiation with the secondary charged particle detector; A method for adjusting the optical axis of a focused ion beam, wherein the position of the ion source is set so that the amount of next charged particles is maximized. 5. The second aperture is capable of changing a size of a through-hole passing through the ion beam,
5. The method for adjusting the optical axis of a focused ion beam according to claim 4, wherein the position of the second aperture is adjusted with respect to the through holes having the respective sizes. 6. An ion source having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for converging the ion beam. A charged particle optical system including a second aperture for regulating the outer shape of the ion beam, an objective lens for further restricting the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, and the focusing A secondary charged particle detector for detecting secondary charged particles generated by irradiating a sample with an ion beam, and a first XY direction moving device for moving the ion source in a direction orthogonal to the optical axis of the ion beam Controlling the first XY direction moving device based on the amount of secondary charged particles detected by the secondary charged particle detector. And a first XY direction movement control means. 7. The first XY-direction movement control means controls the first and second XY-direction movements so that the amount of secondary charged particles detected by the secondary charged particle detector when the ion source moves is maximized. 7. The focused ion beam apparatus according to claim 6, wherein said apparatus controls said XY direction moving apparatus. 8. An ion source having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. A charged particle optical system including a second aperture for regulating the outer shape of the ion beam, an objective lens for further restricting the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, and the focusing A secondary charged particle detector for detecting secondary charged particles generated by irradiating the sample with the ion beam; and a second XY movable with the second aperture in a direction orthogonal to the optical axis of the ion beam. A direction moving device and the second charged particle detector based on the amount of secondary charged particles detected by the secondary charged particle detector.
And a second XY-direction movement control means for controlling the XY-direction movement device. 9. The second XY direction movement control means monitors an amount of secondary charged particles detected by the secondary charged particle detector when the second aperture moves, and controls the secondary XY direction movement. 9. The focused ion beam device according to claim 8, wherein the second XY direction moving device is controlled so that the amount of charged particles is maximized. 10. An ion source section having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. And a second for regulating the outer shape of the ion beam.
A charged particle optical system comprising an aperture and an objective lens which further narrows the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, and a secondary beam generated by irradiating the sample with the focused ion beam A secondary charged particle detector that detects charged particles, a first XY direction moving device that moves the ion source in a direction orthogonal to the optical axis of the ion beam, and a secondary charged particle detector that detects the ion source. The first XY based on the amount of secondary charged particles
First XY-direction movement control means for controlling a direction movement device, a second XY-direction movement device for moving the second aperture in a direction orthogonal to the optical axis of the ion beam, and detection of the secondary charged particle And a second XY-direction movement control means for controlling the second XY-direction movement device based on the amount of secondary charged particles detected by the detector. 11. The first XY direction movement control means includes:
The first XY direction moving device monitors the amount of the secondary charged particles detected by the secondary charged particle detector when the ion source is moved so that the amount of the secondary charged particles is maximized. The second XY direction movement control means monitors the amount of the secondary charged particles detected by the secondary charged particle detector when the second aperture moves, and controls the secondary charging. 11. The focused ion beam device according to claim 10, wherein the second XY direction moving device is controlled so that the amount of particles is maximized. 12. The focused ion beam apparatus according to claim 6, further comprising a hole changing means capable of changing a size of a hole of said second aperture passing through said ion beam. 13. An ion source section comprising an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. And a second for regulating the outer shape of the ion beam.
And a charged particle optical system comprising an objective lens which further focuses the ion beam on the ion beam, a deflection electrode for scanning the focused ion beam, and a secondary beam generated by irradiating the sample with the focused ion beam. A method for adjusting the optical axis of a focused ion beam device having a secondary charged particle detector for detecting charged particles, wherein the focused ion beam is moved while moving the ion source in a direction perpendicular to the optical axis of the ion beam. A method for adjusting the optical axis of a focused ion beam, comprising measuring a current with a Faraday cup and setting the position of the ion source so that the current amount of the focused ion beam is maximized. 14. An ion source section having an ion source for generating an ion beam and an extraction electrode, a first aperture for passing a central portion of the ion beam having a high current density, and a condenser lens for narrowing the ion beam. A charged particle optical system including a second aperture for regulating the outer shape of the ion beam, and an objective lens that further narrows the ion beam to a focused ion beam, a deflection electrode for scanning the focused ion beam, A method for adjusting the optical axis of a focused ion beam device having a secondary charged particle detector for detecting secondary charged particles generated by irradiation, wherein the second aperture is orthogonal to the optical axis of the ion beam. While moving in the direction, the current of the focused ion beam is measured with a Faraday cup, and the focused ion beam is measured. Optical axis adjusting method of the focused ion beam, wherein the amount of current of beam sets the position of the ion source so that a maximum.