JP3392550B2 - Method for measuring deflection angle of charged particle beam and charged particle beam apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a deflection angle of a charged particle beam and a charged particle beam apparatus, and more specifically, to obtain a trajectory of a charged particle beam deflected by a magnetic field, an electric field or the like to obtain charged particles. The present invention relates to a method for measuring a deflection angle of a line, a magnetic field or an electric field distribution, and the like, and a charged particle beam apparatus used therefor.

[0002]

2. Description of the Related Art A technique for measuring a magnetic field distribution in a minute space region by utilizing deflection of a charged particle beam by a magnetic field has been reported. For example, IEE ETransaction on Magnetics, Vol. 28, No. 2, 19
In 1992, reported on pages 1017-1023, the magnetic field distribution is measured using an electron beam. Here, a narrowed electron beam is passed near the magnetic field generation sample surface,
A two-dimensional position detector detects the deflection amount of the electron beam generated by passing through the magnetic field to measure the magnetic field. The obtained deflection amount corresponds to the line integral value of the magnetic field existing in the path through which the electron beam passes. The spatial resolution of the measurement depends on the cross-sectional area of the electron beam passing through the magnetic field.

The information obtained above is the information of the portion of the line in space. In order to obtain the magnetic field distribution on the surface to be measured, information on the surface portion in space is required. Therefore, the electron beam was scanned in the direction of the measurement surface of the magnetic field distribution, and the deflection amount at each position was measured finely. In order to make the sampling distance interval of the electron beam passing through the magnetic field constant, the scanning was performed at a constant scanning speed, and the deflection amount detected by the detector was sampled at constant time intervals. Therefore, the information of the incident position of the electron beam, that is, the sampling distance interval of the measured surface is replaced with the time information. As described above, when the magnetic field distribution on the surface to be measured is measured by scanning the electron beam, the deflection amount is associated with the measured space coordinates at the time when the data is acquired.

[0004]

SUMMARY OF THE INVENTION In the above conventional method,
By using the technique of scanning, the information of the measured position was replaced with the information of time. However, in scanning, as the number of sampling points in the space increases, the number of data acquired in one scanning increases and the measurement time increases. For this reason, when the number of sampling points is increased for measurement in a wide space or high spatial resolution, the measurement time increases, and further, charge accumulation on the sample due to long-time irradiation of the charged particle beam and sample contamination occur. Therefore, there is a problem that accurate information of the sample cannot be obtained.

Therefore, an object of the present invention is to reduce the irradiation time of the charged particle beam to the sample, to accumulate the charge on the sample and to reduce the contamination of the sample. It is to realize the device. Another object of the present invention is to realize a signal processing method for measuring the deflection of a charged particle beam due to a magnetic field or an electric field.

[0006]

To achieve the above object, the charged particle beam deflection measuring method of the present invention irradiates a charged particle beam onto a surface of a reference sample having a finite size, and measures An image is formed to form a reference image, an object to be measured is arranged in the path of the charged particle beam and near the image plane of the reference image, and the reference image is distorted by the object to be measured.
A plurality of two-dimensional images are formed by changing the distance between the object to be measured and the image plane of the reference image, signals of the plurality of two-dimensional sample images are obtained, and respective characteristic points of the two-dimensional sample images are obtained. Between the two-dimensional sample images by using the position information of the detected feature points on the image plane of each two-dimensional sample image and the distance information between the plurality of two-dimensional sample images. Of the line group connecting the characteristic points of each other, which becomes a straight line, the extracted individual straight lines as individual trajectories of the charged particle beam in the three-dimensional space, and the sample to be measured from the above trajectories. Signal processing is performed to obtain the position and deflection angle of the passed charged particle beam on the sample to be measured. Furthermore, if necessary, using the signals of the position and deflection angle on the measured object obtained,
Image processing is performed to display a characteristic distribution image of the object to be measured on the image.

The object to be measured is a magnetic field and an electric field, and the characteristic distribution of the object to be measured is typically a magnetic field or an electric field distribution, but is not limited to these. This method is also applied to those that use transmission means such as light rays, radio waves, electromagnetic waves, sound waves, and ultrasonic waves instead of charged particle beams, and give deflection, reflection, refraction, absorption, scattering, etc. to transmission means instead of electric fields and magnetic fields. The invention can be carried out. The above-mentioned reference sample may be any as long as it produces a contrast capable of extracting feature points from the bright field image, dark field image, lattice image or diffraction image. A particle image, a point on a special pattern, or the like is selected as the characteristic point. When the object to be measured is a magnetic field, a magnetic field having a spatial spread should not reach the image plane.

In order to obtain the straight line from the characteristic points of the plurality of image information, the following signal processing is performed. For each point existing in the three-dimensional space, the nearest point included in the adjacent two-dimensional sample image is found, and the line segment connecting the two feature points, the focused feature point and the found nearest point, is found. The process is performed on at least a plurality of feature points with high possibility. The extracted individual line segments are corrected to form a straight line in the three-dimensional space.

In order to carry out the above method of the present invention,
The charged particle beam device of the present invention passes through a charged particle beam source that generates a charged particle beam having a finite spread, a charged particle beam irradiation unit that irradiates the reference sample with the charged particle beam, and the reference sample. An image plane forming means for forming an image plane by forming an image of a charged particle beam, a sample holding means for holding a sample to be measured which generates a magnetic field or an electric field in the vicinity of the image plane, and a plurality of desired image planes for the image plane. An image forming unit that forms a plurality of sample images by changing the formation position; an image acquiring unit that obtains a signal of the sample image;
An image storage means for storing a signal of the image acquisition means, and a deflection angle of the charged particle beam by the sample to be measured using the signal of the image storage means and an incident position of the charged particle beam on the sample to be measured. And signal processing means for obtaining Further, a video signal processing means for obtaining a magnetic field or electric field distribution image of the object to be measured by using the obtained deflection angle information and incident position information may be added.

The signal processing means carries out the signal processing described in the above measuring method. The image plane forming means and the image forming means are composed of electron lenses, and the distance between the image plane formed by the image plane forming means and the magnetic field is changed by changing the focal length. A preferred form of the sample holding means is one that generates a magnetic field and rotates the magnetic field by 180 degrees or more. The image acquisition means is a two-dimensional image pickup device such as an optical camera. The image obtained by the image acquisition means is an image in which a contrast capable of extracting feature points is formed from the image, and is a bright field image, a dark field image, a lattice image or a diffraction image of the reference sample. A charged particle beam biprism may be used instead of the reference sample.

Further, the apparatus of the present invention may use a beam generating means having a certain spread such as a light beam, a radio wave, an electromagnetic wave, a sound wave and an ultrasonic wave instead of the charged particle beam. At this time, the object to be measured becomes a field or substance that causes deflection of the beam such as deflection, reflection, refraction, absorption, scattering, and attenuation.

[0012]

In the present invention, scanning is not performed, and the charged particle beam having a constant spread emitted from the charged particle beam source is applied to the reference sample having a finite size. Since the charged particle beam that has passed through the reference sample is scattered, it is converged by an electron lens to form an image. The image becomes a bright field image, a dark field image, a lattice image, or a diffractive image door depending on the method and condition of the image formation. This is the reference image. Next, since the sample to be measured such as a magnetic field is arranged in the path of the charged particle beam and near the reference image plane,
The charged particle beam is deflected by a magnetic field or the like and the reference image is distorted. A plurality of reference images thus distorted are obtained by changing the distance between the magnetic field and the image plane, converted into a two-dimensional image signal by the two-dimensional image pickup device, stored in the storage means, and thereafter calculated by the signal processing means. Will be processed. This eliminates the need for scanning, shortens the time for irradiating the sample to be measured with a charged particle beam, and solves the problems of charge accumulation and sample contamination as described in the section of the problem to be solved. .

The deflection angle of the charged particle beam, the intensity distribution of the magnetic field, the electric field and the like are obtained by the following principle. The charged particle beam deflected by the measured object is a straight line in a region where the measured object does not exist. Therefore, if the object to be measured such as a magnetic field is fixed and a plurality of reference images (sample images) in which the reference image is distorted are formed by changing the imaging position in the uniaxial direction, two-dimensional planes of the sample image and the uniaxial direction are formed. It is assumed that the plurality of sample image planes are arranged in parallel in a three-dimensional space formed by one dimension.

The characteristic points of the plurality of sample images are passage points of the charged particle beam on the sample image plane. Therefore, a feature point selected from each of a plurality of image planes of the sample, and the one obtained by connecting the feature points in a straight line can be regarded as the trajectory of the charged particle beam deflected by the magnetic field or the like. In the present invention, first, a straight line group corresponding to the plurality of feature points is obtained from two-dimensional information on the sample image plane and information on the distance between the plurality of sample image planes, and the position and angle of each straight line group in the three-dimensional space are calculated. The position information of the intersection of the test object (with respect to the reference image) and the magnetic field etc. and the straight line group is obtained.

When the positional information of the intersection of the deflection angle of the straight line group and the measured sample surface of the linear group is obtained, the characteristic of the object to be measured at the position of each intersection of the measured sample surface is obtained.
For example, if the characteristic of the object to be measured is a magnetic field and the charged particles are electron beams, the deflection angle due to the Lorentz force due to the magnetic field of the electron beam is proportional to the strength of the magnetic field, so the magnetic field distribution on the surface of the sample to be measured can be obtained. .

The above principle can be applied to the case where the charged particle is a straight traveling wave path and the sample to be measured has a characteristic of deflecting the straight traveling wave path.

[0017]

1 is a block diagram showing the configuration of an embodiment of a charged particle beam device according to the present invention. In this embodiment, an electron beam is used as a charged particle beam, a magnetic field in space is irradiated, feature points are extracted from a plurality of images distorted by the deflection of the charged particle beam by the magnetic field, and an image adjacent to the focused feature point is extracted. The nearest feature point was selected and connected by a straight line to obtain the deflection angle of the electron beam, and the magnetic field distribution in space was measured from the obtained deflection angle.

The electron beam 12 emitted from the electron source 11 is
The reference sample 14 is irradiated through the lens 13. Electrons that have been transmitted through the reference sample 14 and scattered are reflected by the lens 15 and the diaphragm 16.
To form an image on the image plane 17. On the image plane 17, a scattering contrast image of the reference sample 14 (hereinafter abbreviated as reference image) is obtained. The reference image is a bright-field image or a dark-field image that can be identified as a light-dark feature point of the reference sample 14 depending on the shape and position of the diaphragm 16. Therefore, the reference sample 14 is selected so that its contrast image includes a plurality of light and dark contrasts such as particles.

In the vicinity of the image plane 17, the magnetic field 2 to be measured is
The sample holding means 22 holds the sample generating 3 to generate the magnetic field 2
Yields 3. The magnetic field 23 has a spatial spread, but does not exist on the image plane 17 part. The image formed on the image plane 17 is
Due to the influence of the magnetic field 23, a distorted image (hereinafter abbreviated as a sample image) is obtained as compared with the reference image when the magnetic field 23 is not present. The sample image formed on the image plane 17 is magnified by the lens 18 and converted into a two-dimensional image signal by the imaging means 19 such as a camera. The two-dimensional image signal obtained by the image pickup means 19 is stored in the storage means 20 and read from the processing means 21. Although FIG. 1 shows the case where the magnetic field 23 is above the image plane, a similarly distorted sample image can be obtained even when the magnetic field 23 is below the image plane. In this case, if the magnetic fields 23 are the same, the directions of strain will be opposite.

Next, the focal length of the electronic lens 15 is changed,
The image plane 17 of the sample image is moved. The manner of movement of the image plane 17 is schematically shown in FIG. For convenience of explanation, the image plane 17 is defined as an XY plane, and the moving direction of the image plane 17 is defined as a Z direction perpendicular to the XY plane. When the image plane 17 moves in the Z direction and the distance between the magnetic field 23 and the image plane 17 changes from U1 to U2, the image formed on the image plane 17 changes. Electron beam 1
2 is distorted if it is deflected by the magnetic field 23, the magnetic field 2
The amount of distortion increases as the distance from 3 increases. For example, in FIG. 1, it is assumed that the particles of the reference sample 14 are observed by white circles (feature points) drawn on the image plane 17 of FIG. If the image plane moves continuously from U1 to U2, this white circle is observed as if its position were moving. Also, in reality, the image plane 17
Although the magnification of the formed image changes with the movement of
Then, the change in magnification was omitted. By changing the position of the image plane 17 and further changing the focal length of the lens 18 in FIG. 1, the two-dimensional image signal is obtained by the image pickup means 19 as described above. The two-dimensional image signal obtained by the image pickup means 19 is stored in the storage means 20. The processing means 21 uses the information in the storage means 20 to perform the signal processing described below. In FIG. 2, the magnetic field 23
Although the lower image plane 17 is moved downward, the image plane 17 may be moved upward, and the image plane 17 may be moved above the magnetic field 23.
May be formed and used. Furthermore, image plane 1
Even if the movement of 7 crosses the magnetic field 23, the following processing can be performed if the coordinates and the positive and negative directions are correctly obtained.

3, 4, and 5 are diagrams for explaining the information processing method of the storage means 20 and the processing means 21.
FIG. 3 shows three sample images obtained by changing the position of the image plane 17 by the above method. The image planes of the sample images A, B, and C represent images obtained by sequentially changing the focal length of the lens 18 from the side closer to the magnetic field 23. White circle point Ap in the image plane,
Aq ... Cr are feature points (particles) in the image formed by the reference sample 14. These sample images A, B and C
Is stored in the storage means 20 as a two-dimensional image signal via the image pickup means 20. The sample image A is an image formed at an image plane position distant from the center plane of the magnetic field 23 by a distance S0, and the sample image B is formed at an image plane position distant from the sample image A by a distance S1. The sample image C is an image formed at an image plane position separated from the sample image B by a distance S2.
In FIG. 3, for simplification of description, only three particles (characteristic points) of interest are drawn in the sample images A, B, and C, respectively.

Next, with respect to the two-dimensional image signals of the sample images A, B and C stored in the storage means 20, the processing means 21.
The following processing was performed. First, a three-dimensional space is prepared, and the images of the sample images A, B, and C obtained here are arranged at a distance of S1 and S2 as shown in FIG. That is,
The position information of the points of each particle in the sample image is represented as three-dimensional information of X, Y, Z, and characteristic points are extracted from each sample image A, B, and C. In FIG. 4, the characteristic points are indicated by crosses. Here, focusing on the characteristic point Ap of the sample image A, the distance between each characteristic point Bp, Bq, Br in the adjacent sample image B and the characteristic point Ap of the sample image A is calculated. Among these, the feature point Bp closest to the feature point Ap is searched for. 2 of feature points Ap and Bp
The points are connected by a straight line to form a line segment, and such processing is performed on all the other characteristic points Aq and Ar of the sample image A. Similarly, the feature points Bq, Br of the sample image B are
Paying attention also to the above, the nearest point is extracted from the adjacent sample images C, and the signal processing for obtaining the line segment is performed in the same manner as described above. From the line segment connecting the adjacent sample images obtained as described above, that is, between the feature points of the sample images A and B and the sample images B and C, a line segment that becomes one straight line in the entire three-dimensional space Signal processing is performed.

FIG. 5 illustrates the signal processing for obtaining the intensity distribution of the magnetic field 23 to be measured by using the line segment that becomes one straight line in the entire three-dimensional space as the trajectory of the electron beam in which the charged particles are deflected by the magnetic field 23. The conceptual perspective view for doing is shown. Sample image A
From the position to the negative direction of the Z axis, that is, to the electron source side, the distance S0
The sample surface S (the position of the magnetic field to be measured) is assumed to be distant by a distance, and signal processing for extending the straight lines p, m, and n obtained in the three-dimensional space to the sample surface S is performed. This straight line p,
Let m and n be the trajectories of the electron beam deflected by the magnetic field 23, and let the position where the straight lines p, m and n intersect the sample surface S be the incident position of the electron beam on the magnetic field. Further, the inclinations of the straight lines p, m, n in the three-dimensional space and the incident direction of the electron beam 12 were compared, and the angle difference θ was taken as the deflection angle θ of the electron beam by the magnetic field 23.

FIG. 6 is a conceptual perspective view of signal processing for obtaining a straight line segment connecting characteristic points between three or more sample images. First, it is determined whether the line segments u and v obtained from the sample images 17A and 17B are connected to the line segments m and n obtained from the sample images 17B and 17C, respectively, and these are the elements that form a straight line. Perform processing to When it is not a straight line, the line segment u,
Regarding the characteristic points Ea and Eb of the sample image 17A forming v, the second closest point is searched from the characteristic points of the sample image 17B. As a result, the feature point Fb is selected for the feature point Ea, and the feature point Fa is selected for the feature point Eb. These points are connected to form a broken line segment, and line segments Ea-Fb and Eb-
Using Fa, it is examined whether the line segments m and n obtained from the sample images 17B and 17C and the entire three-dimensional space form a straight line. As a result, a straight line including a dotted line portion is formed as shown in FIG. Therefore, instead of the line segments u and v, dotted line segments are adopted and processed as one straight line in the three-dimensional space.

By the above signal processing, information on the incident position of the electron beam on the two-dimensional plane of the sample surface 17S and the three-dimensional deflection angle θ by the magnetic field 23 at the incident position can be obtained. The information on the incident position and the deflection angle θ is further obtained by repeating the above-mentioned processing for the image at each angle by using the rotation function of the sample holding means 22. The vector distribution image of the magnetic field in the cross section of the sample space is obtained by using these three-dimensional deflection angle θ, position information, and the calculation processing of the computer tomographic imaging method.

FIG. 7 is a diagram showing the configuration of another embodiment of the charged particle beam device according to the present invention. In the figure, parts having the same functions as those in FIG. 1 are assigned the same numbers as in FIG. 1 and their explanations are omitted. In this embodiment, as an image used for image processing, the lens 15 of FIG. 1 is adjusted to form a diffraction image on the image plane, and this is used. In the diffraction image, a regular diffraction pattern was used, and the bright points in the pattern were used as the characteristic points in the plurality of sample images. The signal processing for obtaining the straight line connecting the characteristic points in the plurality of sample images and the image processing for obtaining the deflection angle of the sample, the incident position of the irradiation line, the distribution image, etc. from the obtained straight line are the same as those in the embodiment of FIG. is there.

FIG. 8 is a diagram showing the configuration of still another embodiment of the charged particle beam device according to the present invention. In this embodiment, an electron beam biprism 81 is used instead of the reference sample 14. Although only one biprism 81 is shown in FIG. 8, as shown in FIG.
You may comprise so that 1-1 and 81-2 may mutually orthogonally cross. The biprism 81 sandwiches the installed linear electrode 24, and a plate electrode 25 is arranged in parallel to the linear electrode 24 so that the linear electrode 24 and the plate electrode 25 have different potentials. By configuring the two biprisms 81-1 and 81-2 so as to be orthogonal to each other, a lattice pattern is formed on the image plane 17. When a magnetic field is placed as the sample to be measured, distortion occurs in the lattice-like pattern. The points where the grids intersect are used as the feature points used in the image processing described above. Utilizing this distortion, the process of obtaining the trajectory of the electron beam can be performed in the same manner as described above, and therefore, it can be used for the measurement of the magnetic field distribution of the sample to be measured and the process of converting the image.

The embodiment of the present invention has been described above.
The present invention is not limited to the above embodiment. For example, a mask having minute passage holes may be used as the reference sample. In addition, instead of the charged particle beam, a beam that travels straight with a finite spread such as light rays, radio waves, electromagnetic waves, sound waves, and ultrasonic waves is used, and the object to be measured is deflected, refracted, or absorbed by the beam instead of the magnetic field or electric field. It can also be carried out by means of giving scattering, attenuation.

[0029]

As described above, in the measuring method of the present invention, characteristic points of a plurality of images are extracted as data using a charged particle beam having a spread without performing line scanning, and this is extracted in three dimensions. This is a process in which a straight line obtained by arranging in space is used as the trajectory of the charged particle beam, and it is possible to shorten the time for irradiating the sample to be measured with the charged particle beam, and reduce the measurement accuracy due to accumulated charge or contamination of the sample. Further, since the feature points in the image are handled, it is possible to extract the magnetic field information of the fine region from the image containing the information of the magnetic field of the wide region.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a charged particle beam device according to the present invention.

FIG. 2 is a diagram for explaining movement of an image plane for explaining the operation principle of the embodiment shown in FIG.

FIG. 3 is an image diagram of a plurality of samples for explaining the operation principle of the embodiment shown in FIG.

FIG. 4 is a diagram in which a plurality of sample images of FIG. 3 are arranged in a three-dimensional space.

FIG. 5 is a diagram for explaining the processing of one embodiment of the deflection angle measuring method of the present invention.

FIG. 6 is a diagram for explaining the processing of another embodiment of the deflection angle measuring method of the present invention.

FIG. 7 is a configuration diagram of another embodiment of the charged particle beam device according to the present invention.

FIG. 8 is a configuration diagram of still another embodiment of the charged particle beam device according to the present invention.

FIG. 9 is an enlarged perspective view of a main part of the embodiment of FIG.

[Explanation of symbols]

11 ... Electron source 19 ... Imaging means 12 ... Electron beam 20 ... Storage means 13 ... Lens 21 ... Processing means 14 ... Reference sample 22 ... Sample holding means 15 ... Lens 23 ... Magnetic field 16 ... Aperture 81 ... Electron beam biprism 17 ... Image Surface 18 ... Lens

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiro Kuroda 1-280, Higashi Koigokubo, Kokubunji, Tokyo Metropolitan Research Laboratory, Hitachi, Ltd. (72) Inventor Masato Nakajima 3-14-18 Irumacho, Chofu-shi, Tokyo (72) Inventor Hideo Saito 2-31-15 Akamachi, Hachioji City, Tokyo (56) Reference JP-A-5-266214 (JP, A) JP-A-5-109380 (JP, A) JP-A-4-299474 ( JP, A) JP 7-234268 (JP, A) JP 4-206132 (JP, A) JP 8-45465 (JP, A) JP 3-173052 (JP, A) JP 7-335172 (JP, A) JP 5-47337 (JP, A) JP 49-83485 (JP, A) JP 54-114172 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H01J 37/26 G01R 33/028 G21K 1/00 H01J 37/22 501

Claims (4)

(57) [Claims] 1. A surface of a reference sample having a finite size is irradiated with a charged particle beam, and an image of the reference sample is formed to form an image plane, which is the path of the charged particle beam and the image plane. Place the object to be measured in the vicinity of and distorted by the object to be measured 2
A first step of obtaining a signal of the two-dimensional sample image by forming a plurality of two-dimensional sample images in parallel by changing the distance between the object to be measured and the image plane; The second step of detecting the position information of each feature point, the position information of the feature points obtained in the second step, and the distance information between the plurality of parallel two-dimensional sample images are used to detect the plurality of sheets. In the third step of extracting a straight line in a line group connecting mutually parallel two-dimensional sample images, and the extracted individual straight lines as individual trajectories of the charged particle beam in the three-dimensional space. A method for measuring a deflection angle of a charged particle beam, comprising: a signal processing step of obtaining a position and a deflection angle of the charged particle beam on the measurement target which has passed through the measurement target from an orbit. 2. The extraction of a straight line in the third step is performed by selecting the point closest to the focused feature point from the feature points of other sample images adjacent to the sample image including the focused feature point. 2. The method for measuring the deflection angle of a charged particle beam according to claim 1, further comprising: performing a line segment extraction process for obtaining a line segment connecting the focused feature point and the closest feature point obtained. 3. The line segment extraction processing is performed between the first and second sample images and between the second and third sample images, and the feature points of interest in the second sample image and the first sample image are Elements in which the first straight line formed by the feature point and the second straight line formed by the feature point of interest of the second sample image and the feature point of the third sample image form a straight line in the three-dimensional space A first process for determining whether or not
When the first straight line and the second straight line obtained by the first process are straight lines, the straight line to be obtained between the first and third sample images is obtained, and the first straight line and the second straight line are obtained by the first process. Is not a straight line, it is a straight line connecting the feature point of interest of the second sample image and another feature point of the first or third sample image with the second straight line or the first straight line. 3. A second process for forming a straight line by performing correction for obtaining another characteristic point of the first or third sample image forming
The method for measuring the deflection angle of a charged particle beam as described in 1. 4. A charged particle beam source for generating a charged particle beam, a charged particle beam irradiation means for irradiating a reference sample with the charged particle beam with a finite spread, and an image of the charged particle beam passing through the reference sample. An image plane forming means for forming an image plane, a sample holding means for holding a sample to be measured which generates a magnetic field or an electric field in the vicinity of the image plane, and a plurality of image planes formed by changing a plurality of desired forming positions. Image forming means for forming a sample image of the sample image, image acquiring means for obtaining the signal of the sample image, image storing means for storing the signal of the image acquiring means, and the measured object using the signal of the image storing means. A signal processing means for obtaining the deflection angle of the charged particle beam by the sample, and an individual deflection angle of the charged particle beam by the magnetic field or electric field arranged from each of the trajectories and an incident position of the charged particle beam on the magnetic field or the electric field. , The deflection angle and the above Charged particles and wherein the elevation position by comprising signal processing means for obtaining a magnetic field distribution image or field distribution image of space.