JP2005302415A - Scanning transmitted image and magnification of transmitted image/rotation correction method and scanning transmission type electron microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correcting magnifications and rotations of a scanning transmitted image and a transmitted image such that the same magnification and the same rotational angle can be obtained even if the observation of the scanning transmitted image is switched to that of the transmitted image, related to the method for correcting the magnifications and the rotations of the scanning transmitted image and the transmitted image, and a scanning transmission type electron microscope. <P>SOLUTION: A scanning transmission type electron microscope is provided with an optical system in which images are formed on a sample by a scanning optical system, or sample images are formed in front of or behind the sample by irradiating electron beams in probe-shapes across the sample through a scanning optical system. The scanning transmission type electron microscope is configured to provide a magnification/rotational angle correction means 51 to obtain transmitted images with the same magnification/rotation angle based on images obtained by scanning transmitted images. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a scanning transmission image, a magnification / rotation correction method for the transmission image, and a scanning transmission electron microscope.

  FIG. 4 is a diagram showing a configuration example of a general scanning transmission electron microscope. The electron beam emitted from the electron gun 1 is focused by the focusing lens 2 and then deflected by the first scanning coil 3 and the second scanning coil 4. The scanning waveforms of the scanning coils 3 and 4 are created by the surface scanning scan generator 18. The electron beams that have passed through the first and second scanning coils 3 and 4 are imaged on the sample 6 by the objective lens 5. At this time, a part of the electron beam transmitted through the sample 6 is transmitted as it is, but a part is diffracted or scattered by the crystal of the sample.

  A diffraction pattern is created on the back focal plane 8 of the sample. This diffraction pattern passes through the first intermediate lens 9, the second intermediate lens 10, and the third intermediate lens 11 for increasing the magnification, and then enters the dark field detector 14 by the projection lens 12. The dark field detector 14 is provided with an annular fluorescent screen 13. The sample image formed on the annular fluorescent screen 13 of the dark field detector 14 enters the detector control circuit 15. The detector control circuit 15 includes an amplifier 15a and an A / D converter 15b.

  The image signal output from the dark field detector 14 is amplified by the amplifier 15a and then converted into digital data by the subsequent A / D converter 15b. The image signal converted into digital data is stored in an area corresponding to the probe position in the frame memory 17. Data forming the image data is read from the frame memory 17 by the CPU 20 and displayed on the monitor 21. BS is a bus to which a scan generator 18 for surface scanning, a frame memory 17, a monitor 21, a CPU 20, a TEM operation panel 16 and a detector control circuit 15 are connected.

  A transmission electron microscope that forms an image by the interaction of electrons is enlarged by a lens action by a magnetic field / electric field after the electrons have passed through the sample. The electrons that have passed through the sample 6 are magnified by the intermediate lenses 9 to 11 and the projection lens 12, and the magnified image is projected on a fluorescent plate, a photographic film, or a television camera located about 100 to 500 mm away from the projection lens.

  A plate-shaped recording medium such as a photographic dry plate, a photographic film, or an image plate is disposed at a position several tens of millimeters below. Furthermore, a television camera (TV camera) is fixed and attached at a certain angle with respect to the sample moving direction at a position of several tens of millimeters below. The photographic film and TV camera located below the fluorescent screen is further magnified than seen on the fluorescent screen. Here, the electromagnetic lens provides not only an image enlargement effect but also an image rotation effect. For this reason, recently developed transmission electron microscopes eliminate the apparent image rotation and obtain the required magnification, so that the lens action of each of the lenses in the imaging system and the accompanying image rotation by each lens. It is set considering the amount.

  In the scanning transmission electron microscope, an electron beam is focused in a probe shape by a focusing lens, and the electron beam is scanned and irradiated on a sample by a focusing lens deflection coil. The electrons that have passed through the sample are captured by the detector, and the irradiation position on the sample and the relative position of the display screen are matched to display the image as an image. The amount of electrons entering the detector is converted into image shading and displayed.

As a conventional apparatus of this type, there is known an apparatus that can shorten the time required for visual field search when displaying an SEM / STEM image and a TEM image (see, for example, Patent Document 1).
JP 2002-343294 A (page 4, page 5, FIG. 1)

  The electromagnetic lens not only enlarges the image but also rotates the image. Therefore, in order to eliminate the apparent image rotation and to obtain the required magnification, the multiple lenses of the imaging system and the size of each lens action are changed, and there is no image rotation accompanying the magnification change. Designed as such. Recent electron microscopes can observe not only a transmission image but also a scanning transmission image. The scanning transmission image is easy to set because the image rotation and magnification are electrically set.

  On the other hand, in the transmission image, the required magnification is obtained by a combination of a plurality of lenses, but in order to obtain a result that satisfies both the magnification and rotation angle requirements required by the scanning transmission image and the transmission image, It took a lot of time. For this reason, in a transmission image, the rotation angle is almost constant with respect to the magnification, and when the scanning transmission image is observed while being rotated, the magnification is only one when switched to the transmission image. Although it does, most of the images rotate differently. Although it is possible in principle to hold the current data of the lens for adjustment at each rotation angle even at the same magnification, the required data becomes enormous and is not realistic.

  The present invention has been made in view of such a problem. Even when switching from scanning transmission image observation to transmission image observation, the scanning transmission image and the transmission image are obtained so that the same magnification and the same rotation angle can be obtained. An object of the present invention is to provide a magnification / rotation correction method and a scanning transmission electron microscope.

  The invention according to claim 1 obtains a two-dimensional Fourier phase image of the obtained scanning transmission image and transmission image, and adjusts the current flowing through the optical system so that both Fourier phase images match, Even when the scanning transmission image is switched to the transmission image observation, the same magnification and the same rotation angle can be obtained.

  The invention described in claim 2 is provided with an optical system that forms an image on the sample by a scanning optical system or irradiates the sample with an electron beam in the form of a probe and forms an image of the sample in front of or behind the sample. The scanning transmission electron microscope is characterized in that magnification / rotation angle correction means for obtaining a transmission image having the same magnification / rotation angle based on the image obtained by the scanning transmission image is provided.

  According to a third aspect of the present invention, the magnification / rotation angle correcting means obtains a two-dimensional Fourier phase image of the obtained scanning transmission image and transmission image, and the optical system is configured so that the two Fourier phase images coincide with each other. The current flowing is adjusted.

  According to the first aspect of the invention, the magnification / rotation angle correcting means operates based on the image obtained by the scanning transmission image so that the magnification and the rotation angle of the transmission image coincide with those of the scanning transmission image. Even when the scanning transmission image observation is switched to the transmission image observation, the same magnification and the same rotation angle can be obtained.

  According to the second aspect of the present invention, the magnification / rotation angle correction unit compares the obtained scanning transmission image with the transmission image and operates so as to obtain the same magnification / rotation angle. Image) and the scanning transmission image (STEM image) can be made to coincide with each other.

  According to the third aspect of the present invention, a two-dimensional Fourier phase image of the obtained scanning transmission image and transmission image is obtained, and the current flowing through the optical system is adjusted so that the two Fourier phase images coincide with each other. Thus, both rotation angles can be matched.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a system configuration example for carrying out the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals. In the figure, reference numeral 1 denotes an electron gun, which is composed of an acceleration tube (Acc Tube) and electron gun alignment coils GA1 and GA2. 2a and 2b are focusing lenses; 22 is a focusing lens adjustment lens; 23 and 24 are deflection adjustment lenses for the focusing lens; 6 is a sample; and 25 is a secondary electron detection that detects secondary electrons emitted from the surface of the sample 6 , 7 is an objective lens disposed behind the sample 6, 33 is a condenser lens, IS1 and IS2 are image shift coils, 9 is a first intermediate lens, 10 is a second intermediate lens, 11 is a third intermediate lens, 12 Is a projection lens, and PLA is a deflection lens of the projection lens. The intermediate lenses 9 to 11 are used for image enlargement. Although not shown, an objective lens is provided in front of the sample 6.

  Reference numeral 26 denotes a TV camera for photographing a transmission image from the sample 6, 27 denotes a detector for detecting a bright field image, 28 denotes a detector for detecting a dark field image, and 29 denotes a TV installed at a position farther from the TV 1. Camera 2. Reference numerals 30 to 32 denote apertures provided at respective predetermined locations. Reference numeral 40 denotes a lens power supply for driving the lens, 41 denotes an alignment power supply for driving the alignment coil, and 42 denotes a detector power supply for supplying power to the various detectors 25, 27, and 28. 43 is an electron gun power source for supplying power to the electron gun 1, 44 is a TV power source for supplying power to the TV cameras TV1 and TV2, 45 is a skin amplifier for amplifying signals from the detectors 25, 27 and 28, 46 Is an aperture power supply for supplying power to the apertures 30-32.

  Reference numeral 50 denotes a computer that controls the overall operation, and 51 denotes a control unit provided in the computer 50. The control unit 51 characterizes the present invention, and can be realized by software, for example. 52 is a memory for storing various information, 53 is a lens interface connected to the lens power supply 40, 54 is an alignment interface connected to the alignment power supply 41, 55 is an aperture interface connected to the aperture power supply 46, and 56 is a detector power supply. 42, a detector interface connected to 42, 57 an electron gun interface connected to the electron gun power supply 43, 58 a TV interface connected to the TV power supply 44, and 59 a scan interface connected to the amplifier 45.

Reference numeral 60 denotes a display unit (GUI: Graphical User Interface) for displaying various information, 61 denotes an operation panel connected to the computer 50, 62 denotes a mouse as a coordinate input device, and 63 denotes a keyboard for inputting various commands.
(When obtaining a transmission image)
In order to enlarge an image formed by the electron beam transmitted through the sample 6, the objective lens 7, the intermediate lenses 9 to 11 and the projection lens 12 are arranged behind the sample. A TV camera 26 (TV1) is provided at a distance from the final lens of the imaging system and the projection lens 12, and a TV camera 29 (TV2) is provided at a position different from TV1.

  Upon receiving the designation of magnification from the user, the control unit 51 outputs information on the amount of current necessary for each imaging system lens, and outputs information for selecting a TV camera. A lens power source 40 that converts current amount information from the control unit 51 into an actual current and a lens interface 53 that performs these communications are provided.

A TV power supply 44 and its interface 58 are provided for receiving TV camera selection information and causing the display unit 60 to display an image of the camera that has entered the optical axis. A detector power source 42 for receiving and selecting TV camera selection information and taking the camera in and out of the optical axis, and its interface 56 are provided. An operation panel 61 for performing image selection, axis alignment, and operation, a mouse 62, and a keyboard 63 are provided.
(When obtaining a scanning transmission image)
Focusing lenses CL1 and CL2 and an adjustment lens 22 for giving an electron beam probe diameter irradiated on the sample 6 and deflection coils 23 and 24 for changing the scanning position are arranged in front of the sample 6. In addition, detectors 27 and 28 for capturing electrons that have passed through the sample 6 are provided. A control unit 51 for selecting the magnification from the user, changing the size of the scanning area and selecting the image type, and a detector power source 42 for receiving and inserting the detector upon receiving the image type selection information. And a detector interface 56 for performing communication between the power source and the control unit 51.

  In addition, an amplifier 45 for amplifying the intensity of the obtained signal, a display unit 60 on which operation information and an observation image are displayed, an operation panel 61 for performing image selection, axis alignment, and operation, a mouse 62, and a keyboard 63. Is provided. An outline of the operation of the apparatus configured as described above is as follows.

  The electron beam emitted from the electron gun 1 is focused by the focusing lenses 2 a and 2 b, adjusted by the condenser lens adjusting lens 22, and then irradiated on the sample 6. After the secondary electrons emitted from the surface of the sample 6 are detected by the secondary electron detector 25, the secondary electrons are input to the computer 50 through the detector interface 56, visualized as necessary, and then displayed on the display unit. 60.

  On the other hand, the electron beam that has passed through the sample passes through the objective lens 7 and enters the intermediate lenses 9 to 11 that continue through the adjustment lens 33. These intermediate lenses 9 to 11 enlarge the magnification of the image. The focused electron beam is projected onto the TV 1 by the projection lens 12. The transmitted image is detected by the bright field detector 27 and the dark field detector 28, amplified by the amplifier 45, input to the computer 50 through the scan interface 59, and displayed on the display unit 60. Since the TV 2 is installed farther from the sample than the TV 1, an image with a large magnification can be taken.

  In the system configured as described above, the scanning transmission mode (STEM mode) and the transmission mode (TEM mode) are switched as necessary by a command from the keyboard 63. As a result of this operation, the same magnification and the same rotation angle can be obtained even when the scanning transmission image observation is switched to the transmission image observation.

  FIG. 2 is a diagram showing a state of magnification enlargement. The same components as those in FIG. 1 are denoted by the same reference numerals. Power is supplied from the lens power source 40 to the objective lens 7, the intermediate lenses 9 to 11, and the projection lens 12. After the electron beam transmitted through the sample is focused by the objective lens 7, the image is magnified by the intermediate lenses 9 to 11 and projected from the projection lens 12 onto the TV1 driver 26a and the TV2 driver 29a. The transmission images detected by the TV 1 and TV 2 are notified to the control unit 51 through the TV power source 44 and the TV interface 58. On the other hand, the detector power source 42 is notified to the control unit 51 via the detector interface 56. The magnification of the transmission image is L5 <L6 when the distances from the projection lens to TV1 and TV2 are L5 and L6, respectively. Therefore, the magnification of the image taken by TV2 is high.

  Hereinafter, the operation of the present invention will be described in detail. FIG. 3 is a diagram illustrating a configuration example of an electromagnetic lens. In the figure, 71 is a yoke, and 72 is a coil wound around the yoke 71. If the gap (hole diameter) between the yokes is bmm, the distance between the pole pieces is smm, and the focal length of the lens is fmm, the following equation is obtained.

f = 25 (s + b) / ((NI) ² / U)
Here, U is a relativistic corrected voltage of incident electrons. In general, since the opening angle of the electron beam is very small, the lens can be approximated as an optical thin lens. In this case, if the object plane distance is X, the image plane distance is Z, and the focal length is f, Newton's thin lens formula (1 / f) = (1 / X) + (1 / Z)
Is applicable.

Now, the distance from the sample to the objective lens principal plane X _OL, the distance to the objective lens OL~ intermediate lens 9 (IL1) L1, the distance from the intermediate lens IL ₁ to the intermediate lens 10 (IL2) L2, the intermediate lens When the distance from 9 (IL ₂ ) to the intermediate lens 11 (IL ₃ ) is L3, the distance from the intermediate lens IL3 to the projection lens 12 (PL) is L4, and the distance from the projection lens PL to the TV camera is L5, It became.

L ₁ = Z _OL −X _IL1 , L ₂ = Z _IL1 −Z _IL2 ,
L ₃ = Z _IL2 −X _IL3 , L ₄ = Z _IL3 −X _PL
Here, Z _OL represents the distance from the lens principal surface to the image plane, and X _IL represents the distance from the lens principal surface to the object surface.

An objective lens (OL) 7 to I _OL (A), IL ₁ to I _IL1 (A), I _IL2 into IL ₂ (A), IL3 to I _IL3 (A), the projection lens (PL) 12 to I _PL (A each lens focal length at a current of) the _{f OL, f IL1, f IL2} , f IL3, f PL. At this time, when the TV 1 is used, the magnification M that is enlarged in the imaging system is
M = M _OL・ M _IL1・ M _IL2・ M _IL3・ M _PL
= (Z _OL / X _OL ) ・ (Z _IL1 / X _IL1 ) ・ (Z _IL2 / X _IL2 ) ・ (Z _IL3 / X _IL3 ) ・
(Z _PL / X _PL )
It becomes. Here, in order not to change the focus of the objective lens (OL) even if the magnification is changed, the values relating to the objective lens OL, X _OL , Z _OL , and f _OL need to be constant. If the values X _PL , Z _PL , and f _{PL of} the projection lens are also constant, only IL ₁ , IL ₂ , and IL ₃ need be varied.

When I (A) current is passed through the lens,
θ = 10.68NI / √U
Only known to rotate. Here, θ is (deg), N is the number of turns of the coil, NI is an ampere turn (AT), and U is an acceleration voltage corrected for relativity. If the polarity of the current I (A) is reversed, it rotates in the opposite direction.

Since the sum of the rotation angles of the respective lenses is the rotation angle of the observation image, in this case, the total rotation angle θ is
θ = (10.68 / √U). (N _OL I _OL + N _IL1 I _IL1 + N _IL2 I _IL2 + N _IL3 I _IL3 + N _PL I _PL )
It becomes.

  The actual operation is as follows. Here, as a premise, the STEM image when scan rotation is not performed has the same field of view as the TEM image and the same rotation angle if the magnification is the same.

  The magnification of the scanning transmission image (STEM image) is set by the observer using the GUI 60a of the display unit 60, the operation panel 61, the mouse 62, and the keyboard 63. The control unit 51 receives the value, and, for example, a necessary detector is determined and selected by software, and the information is sent to the detector interface 56 and the detector power source 42, and the selected detector enters the optical axis. .

  A signal from the detector selected by the control unit 51 is input via the amplifier 45 and is formed into an image via the scan interface 59. In addition, information on the amount of current necessary for each lens is output from the control unit 51 to the lens interface 53 and the lens power supply 40, and a current value is set in the lens coil.

  Usually, the size of the scanning region is changed for each magnification, and the current value of each lens set for this purpose is one. Therefore, the data can be stored in the memory 52 in the computer 50, and necessary information can be read according to the magnification. When scan rotation is performed, it can be handled by changing the scanning direction. The image obtained here is stored in the control unit 51.

  If necessary, the STEM image (scanning transmission image) is switched to the TEM image (transmission image). When the scan rotation is not performed, the rotation angles of the STEM image and the TEM image are the same. The control unit 51 receives a value such as a magnification at that time, and a necessary camera is determined and selected by software, for example, and the information is sent to the detector interface 56 and the detector power source 42, and the selected TV camera is on the optical axis. to go into.

  An image from the TV camera selected by the control unit 51 is input to the computer 50 via the TV camera, the TV power supply 44, and the TV interface 58. In addition, information on the amount of current necessary for each lens is output from the control unit 51 to the lens interface 53 and the lens power supply 40, and a current value is set in the lens coil.

  Here, the image obtained by STEM and the image obtained by TEM are compared. At this point, the magnification is the same and only the rotation angle is different. Therefore, a two-dimensional Fourier phase image is obtained for each of the STEM image and the TEM image. For example, the Fourier phase image of the TEM image is rotated to find a rotation angle that matches the Fourier phase image of the STEM image. Here, the Fourier phase image is an image obtained by performing inverse Fourier transform on only the term related to the phase of the Fourier transform image, and is a preferable method for comparing the characteristics of the observed images.

Fourier transform images F (ξ, η) and H _i (ξ, η) of observed images (here, TEM image f (x, y) and reference image (here, STEM image) h _i (x, y)) Using absolute value distributions | F (ξ, η) |, | H _i (ξ, η) | and phase distributions Φ _F (ξ, η), Φ _Hi (ξ, η),
F (ξ, η) = | F (ξ, η) | exp [−jΦ _F (ξ, η)]
H _i (ξ, η) = | H _i (ξ, η) | exp [−jΦ _Hi (ξ, η)] (i = 1 to M)
Image obtained by inverse Fourier transform of only the term related to phase fΦ (x, y) = Fr ⁻¹ {exp [−jΦ _F (ξ, η)]}
h _i Φ (x, y) = Fr ⁻¹ {exp [−jΦ _Hi (ξ, η)]} (i = 1 to M)
Defined by Here, Fr ⁻¹ {} indicates inverse Fourier transform. The similarity g _i is the cross-correlation g _i (x, y) = Fr ⁻¹ {exp [− of the Fourier phase image fΦ (x, y) of the observed image and the Fourier phase image h _i Φ (x, y) of the reference image. j (Φ _F (ξ, η) −Φ _Hi (ξ, η))]} (i = 1 to M) (1)
Is used. With this formula, similarity and position estimation can be performed simultaneously.

  Alternatively, the TEM image is simply rotated, the difference between the images is taken, and the coincident rotation angle is found. Each lens current is adjusted so that the angle and direction required for the rotation of the TEM image and the total rotation angle by each lens are constant at this angle. Since each lens has a specific current direction, the increase / decrease direction of each lens current can be determined by the direction of rotation required.

Now, _assuming that the excitation of the objective lens 7 and the projection lens 12 is constant, X _IL1 and Z _IL3 are constant values. Therefore, if only the intermediate lenses 9 to 10 (IL _{1 to} IL ₃ ) are varied. Good. If excitation of two of these lenses is arbitrarily determined, the remaining lens must be focused, so that the focal length is uniquely determined.

  The rotation angle obtained under these conditions is compared with the required rotation angle to confirm that they match. If they do not match, another condition is searched. Since the rotation angle closely matches the mathematical formula, it can be processed only by calculation. The STEM image and the TEM image are displayed on the display unit 60 using these conditions. In this state, the rotation of the displayed image coincides. This image is compared with a STEM image or a TEM image (which has the same rotation angle as the STEM image) used to obtain the rotation angle. This comparison is performed by comparing Fourier phase images and images.

  Next, the magnifications of the obtained images are compared to check whether they are within an allowable range. If it is out of tolerance, look for other conditions to match the magnification. Note that the field of view may be shifted due to the rotation. In this case, the control unit 51 finds the direction of deviation from the comparison of the phase images, and moves the field of view using the image shift coil (coil of the intermediate lenses 9 to 11) so as to match. The moving direction of the image by the image shift coil also changes depending on the rotation angle, but since the direction is the same as the rotation of the TEM image, it can be seen in which direction it should be moved.

  An image can be obtained as described above. Here, if display of STEM images, rotation, and creation of TEM image data at each rotation angle are repeated, enormous lens data can be created automatically. This lens data is stored in the memory 52.

  As described above, since the similarity between the STEM image and the TEM image is expressed by the expression (1), the control unit 51 checks the similarity between the STEM image and the TEM image. For example, when the TEM image is adjusted using the STEM image as a reference, feedback is applied to the intermediate lens system so that the similarity (magnification / rotation angle) of the two coincides. In this way, the control unit 51 operates based on the STEM image so that the magnification and the rotation angle of the TEM image coincide with the STEM image. Therefore, even when the STEM image is switched to the TEM image, the same magnification An image with the same rotation angle can be obtained.

  In the above description, the case where the rotation angles of the STEM image and the TEM image coincide with each other has been described. However, the present invention is not limited to this, and an SEM image can be used instead of the STEM image. However, since it is necessary to compare only the shapes, a technique such as using a Fourier phase image is required.

  The present invention is used in the fields related to transmission electron microscopes and scanning transmission electron microscopes.

It is a figure which shows the system configuration example which implements this invention. It is operation | movement explanatory drawing of this invention. It is a figure which shows the structural example of an electromagnetic lens. It is a figure which shows the structural example of a general scanning transmission electron microscope.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electron gun 2a Focusing lens 2b Focusing lens 6 Sample 7 Objective lens 9 1st intermediate lens 10 2nd intermediate lens 11 3rd intermediate lens 12 Projection lens 22 Adjustment lens 23 Deflection lens 24 Deflection lens 25 Secondary electron detector 26 TV camera 1
27 Dark Field Image Detector 28 Bright Field Image Detector 29 TV Camera 2
30 Aperture 31 Aperture 32 Aperture 40 Lens Power Supply 41 Alignment Power Supply 42 Detector Power Supply 43 Electron Gun Power Supply 44 TV Power Supply 45 Amplifier 46 Aperture Power Supply 50 Computer 51 Control Unit 52 Memory 53 Lens Interface 54 Alignment Interface 55 Aperture Interface 56 Detector Interface 57 Electronic Gun interface 58 TV interface 59 Scan interface 60 Display unit 61 Operation panel 62 Mouse 63 Keyboard

Claims (3)

In a scanning transmission electron microscope provided with an optical system that forms an image on a sample with a scanning optical system or irradiates the sample with an electron beam in the form of a probe and forms a sample image in front of or behind the sample.
Based on the image obtained by scanning transmission image, when obtaining transmission image of the same magnification and rotation angle,
A scanning transmission image obtained by obtaining a two-dimensional Fourier phase image of the obtained scanning transmission image and transmission image, and adjusting the current flowing through the optical system so that the Fourier phase images of the two images coincide with each other. And magnification / rotation correction method for transmission images. In a scanning transmission electron microscope provided with an optical system that forms an image on a sample with a scanning optical system or irradiates the sample with an electron beam in the form of a probe and forms a sample image in front of or behind the sample.
A scanning transmission electron microscope comprising a magnification / rotation angle correcting means for obtaining a transmission image having the same magnification / rotation angle based on an image obtained by a scanning transmission image.   The magnification / rotation angle correction means obtains a two-dimensional Fourier phase image of the obtained scanning transmission image and transmission image, and adjusts the current passed through the optical system so that the Fourier phase images of the two coincide. The scanning transmission electron microscope according to claim 2.

Images