JP5670096B2 - Method and apparatus for acquiring three-dimensional image of sample using tomography method - Google Patents

Description

The present invention relates to a method and apparatus for obtaining a three-dimensional image of a sample using the tomography method, and more specifically, a three-dimensional image of the sample using the tomography method that suppresses the influence of beam broadening and improves the resolution in the sample thickness direction. The present invention relates to an acquisition method and apparatus.
Method and apparatus

  By applying computer tomography (CT) to a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) on a nanometer-scale three-dimensional structure, three-dimensional structural observation and structural analysis can be performed. Techniques that make it possible (TEM tomography and STEM tomography) are well known.

  FIG. 17 is a schematic diagram of TEM tomography / STEM tomography. In this method, first, the sample 1 is tilted at various angles using a TEM or STEM to obtain a TEM image or an STEM image. For example, if the tilt angle is ± 60 degrees and tilted one degree at a time, and a TEM image or a STEM image is acquired at the same time, the total acquired tilt image is 121 sheets. By applying the CT method to the acquired tilt image series, a reconstructed cross-sectional image is obtained. A three-dimensional image is obtained by superposing the obtained series of reconstructed sectional images.

  As a conventional apparatus of this type, in an electron microscope having a transmission electron microscope image observation mode and a scanning electron microscope image observation mode, a sample processed by a focused ion beam apparatus is scanned by a scanning electron of a target processing portion in an SEM mode. A technique is known in which when a desired scanning electron image is found by searching for an image, the portion is switched to a transmission electron microscope image observation mode to obtain a transmission image (see, for example, Patent Document 1).

Japanese Patent No. 4111778 (paragraphs 0042-0054, FIGS. 1 and 4)

  When obtaining a three-dimensional image by TEM tomography or STEM tomography, the larger the sample thickness, the more three-dimensional information is obtained. However, when obtaining a highly quantitative three-dimensional image, there is a limit to a certain sample thickness, and there are two causes. The first cause is that the sample is too thick and the electron beam does not pass through the sample, making it difficult to obtain a TEM image or STEM image.

This problem can be solved by increasing the acceleration voltage. The second cause is that if the sample is too thick, chromatic aberration occurs in the case of TEM, and the resolution of the TEM image decreases. In the case of STEM image, the electron beam e ⁻ The spatial resolution decreases with the transmission distance. FIG. 18 is an explanatory diagram of beam broadening. In the shallow part of the sample 1, the electron beam has a small diffusion, and in the deep part of the sample 1, the diffusion is large. For this reason, the spatial resolution of the sample is remarkably deteriorated in a portion where diffusion is large.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a sample three-dimensional image acquisition method and apparatus using a tomography method capable of improving resolution.

  In order to solve the above-described problems, the present invention has the following configuration.

(1) In the invention according to claim 1, in the scanning transmission electron microscope, the sample is tilted and a first three-dimensional image of the sample is obtained using a computer tomography method, and then the sample is turned over and the sample is tilted. Te to obtain a second three-dimensional image of the sample by using a computer tomography method, an image obtained by cutting out the upper half of the first three-dimensional image of the resulting sample, on the second three-dimensional image of the sample A synthesized three-dimensional image of the sample is obtained by synthesizing the half-cut image .

(2) The invention according to claim 2 is provided with a three-dimensional image acquisition means for obtaining a three-dimensional image of the sample in the scanning transmission electron microscope, and the first three-dimensional image of the sample using the three-dimensional image acquisition means. Next, the sample is turned over to obtain a second three-dimensional image of the sample using the three-dimensional image acquisition means, and an image obtained by cutting out the upper half of the first three-dimensional image of the obtained sample ; A synthesized three-dimensional image of the sample is obtained by synthesizing an image obtained by cutting out the upper half of the second three-dimensional image.

  (3) The invention described in claim 3 is characterized in that a sample rotation mechanism for automatically turning over the sample is provided.

(4) In the invention according to claim 4, in the scanning transmission electron microscope, the sample is tilted to obtain a first reconstructed cross-sectional image of the sample using a computer tomography method, and then the sample is turned over to tilt the sample. Then, using the computed tomography method, a second reconstructed cross-sectional image of the sample is obtained, the first reconstructed cross-sectional image is Fourier transformed to obtain a first Fourier transform image, and the second reconstructed cross-sectional image is obtained. Rotation processing and Fourier transform processing are performed on the second Fourier transform image, and the first Fourier transform image and the second Fourier transform image are added to obtain a third Fourier transform image. A reconstructed cross-sectional image obtained by performing inverse Fourier transform on the third Fourier transform image is obtained.

(5) The invention according to claim 5 is the scanning transmission electron microscope, wherein a reconstructed cross-sectional image acquiring means for obtaining a reconstructed cross-sectional image of the sample is provided, and the first of the sample is obtained using the reconstructed cross-sectional image acquiring means. A Fourier transform unit that obtains a reconstructed cross-sectional image, then turns the sample over, obtains a second reconstructed cross-sectional image of the sample using the reconstructed cross-sectional image acquisition unit, and Fourier transforms the reconstructed cross-sectional image of the sample; provided, the first reconstructed cross-sectional image by Fourier transform by using the Fourier transform means to obtain a first Fourier transform image, the rotation process and the Fourier transform means with respect to the second reconstructed cross-sectional image The second Fourier transform image is obtained by performing the Fourier transform processing used , and an addition means for obtaining the third Fourier transform image by adding the first Fourier transform image and the second Fourier transform image is provided. The third hood that is the output of the means The inverse Fourier transform means for inverse Fourier transform of e converted image provided, characterized in that it is configured to output the inverse Fourier transform means such that the final reconstructed cross-sectional image.

(6) invention of claim 6, obtains the inclination STEM image series, to obtain a first reconstructed cross-sectional image for a particular region of the sample by applying the CT method, then the turned over specimen again for a particular area, and obtains the inclination STEM image series, give a second reconstructed cross-sectional image by applying the CT method, the second reconstructed cross-sectional image to be the same direction as the first reconstruction sectional image , And the third reconstructed cross-sectional image is obtained by adding the first reconstructed cross-sectional image and the rotated second reconstructed cross-sectional image in real space.

(7) The invention according to claim 7 provides a reconstructed cross-sectional image obtaining means for obtaining a reconstructed cross-sectional image of a sample in a scanning transmission electron microscope, and the reconstructed cross-sectional image obtaining means is used for a specific region of the sample. obtain a first reconstructed cross-sectional image, then turned over a sample using the reconstructed cross-sectional image acquisition unit to obtain a second reconstructed cross-sectional image for the particular region of the sample, the first reconstructed sectional images The second reconstructed cross-sectional image is rotated so as to be in the same direction as that of the first reconstructed cross-sectional image and the second reconstructed cross-sectional image are added in real space. And a third reconstructed cross-sectional image is obtained by adding the first reconstructed cross-sectional image and the rotated second reconstructed cross-sectional image in real space.

  The present invention has the following effects.

  (1) According to the first aspect of the present invention, a three-dimensional image of half of the sample from the front side and half of the sample from the reverse side is obtained and a three-dimensional image of the sample is obtained from these images. A three-dimensional image with good resolution can be obtained at any part in the thickness direction of the sample.

  (2) According to the second aspect of the present invention, a three-dimensional image of a half is obtained from the front side of the sample, and the sample is turned upside down to obtain a three-dimensional image of the sample from these images. A three-dimensional image with good resolution can be obtained at any part in the thickness direction of the sample.

  (3) According to the invention described in claim 3, since the sample rotation mechanism for automatically turning over the sample is provided, the sample can be turned over with good operability.

  (4) According to the invention described in claim 4, the reconstructed cross-sectional image obtained in claim 1 is subjected to Fourier transform, and the result obtained by adding the two reconstructed cross-sectional images subjected to Fourier transform is further reversed. Since the reconstructed cross-sectional image is obtained by Fourier transform, it is possible to obtain a three-dimensional image having a uniform spatial resolution in the sample thickness direction and higher quantitativeness than in the case of claim 1.

  (5) According to the invention described in claim 5, the first reconstructed cross-sectional image of the sample is obtained using the reconstructed cross-sectional image obtaining means, and then the sample is turned over and the reconstructed cross-sectional image obtaining means is used. The second reconstructed cross-sectional image of the sample is obtained, the Fourier transform of the first reconstructed cross-sectional image and the second reconstructed cross-sectional image of the obtained sample is obtained, and the result obtained by adding these Fourier transforms is the inverse Fourier transform Since the final three-dimensional image is obtained using the means, it is possible to obtain a three-dimensional image having a uniform spatial resolution in the sample thickness direction and having a high quantitativeness as compared with the case of claim 2.

  (6) According to the invention described in claim 6, a reconstructed cross-sectional image having a uniform spatial resolution can be obtained by adding the reconstructed cross-sectional images obtained by photographing from the front and back surfaces of the sample in real space. Can do.

  (7) According to the invention described in claim 7, a reconstructed cross-sectional image having uniform spatial resolution can be obtained by adding the reconstructed cross-sectional images obtained by photographing from the front and back surfaces of the sample in real space. Can do.

It is explanatory drawing of the high-resolution tomography method by this invention. It is explanatory drawing of the acquisition method of the three-dimensional image of the sample back surface using the conventional sample holding stand. It is a schematic diagram of the sample holding stand with an automatic rotation mechanism. It is a figure which shows the STEM image of the ABS resin of the same area | region which reversed and photographed the STEM image of the ABS resin of 1 micrometer thickness, and the sample. It is a figure which shows a reconstruction cross-sectional image. It is a figure which shows the xy slice image of a three-dimensional image. It is an expanded view from a three-dimensional image. It is explanatory drawing of the other high resolution tomography method by this invention. It is a figure which shows the STEM image of ABS resin. It is a figure which shows the reconstruction cross-sectional image obtained by applying CT method to an inclination STEM image series. It is a figure which shows a Fourier-transform image. It is a figure which shows the Fourier-transform image and reconstruction cross-sectional image which were obtained by this invention. It is explanatory drawing of the other high resolution tomography method by this invention. It is a figure which shows the STEM image of ABS resin. It is a figure which shows the reconstruction cross-sectional image obtained by applying CT method to an inclination STEM image series. It is a figure which shows the reconstruction cross-sectional image obtained by this invention. It is a schematic diagram of TEM tomography and STEM tomography. It is explanatory drawing of beam broadening.

Example 1
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The scanning transmission electron microscope (STEM) used in the present invention is an existing one that is conventionally known. FIG. 1 is an explanatory view of a high resolution tomography method according to the present invention. The present invention includes a sample holder having a high tilt mechanism, an external computer that controls acquisition of an electron microscope image, and a program for calculating the acquired image. The above configuration is common to the embodiments described below.

  First, a three-dimensional image circle 1 is obtained using ordinary STEM tomography. The upper half of the obtained three-dimensional image circle 1 that is less affected by the reduction in spatial resolution due to beam broadening is cut out to obtain a three-dimensional image circle 1 '. FIG. 1A shows the three-dimensional image circle 1 ′ thus obtained.

  Next, the sample 1 is turned over to obtain the three-dimensional image circle 2 by using STEM tomography on the same region where the three-dimensional image circle 1 is obtained. Similarly, the upper half of the obtained three-dimensional image circle 2 is cut out and further rotated by 180 degrees with respect to the cut-out three-dimensional image to obtain a three-dimensional image circle 2 '. The method of rotating the image by 180 degrees can be performed using an existing image processing technique. FIG. 1B shows the three-dimensional image circle 2 ′ obtained in this way. Next, the three-dimensional image circle 1 'and the three-dimensional image circle 2' are combined to obtain a three-dimensional image circle 3 as shown in FIG. With the above method, it is possible to obtain a highly quantitative three-dimensional image by suppressing a decrease in resolution due to beam broadening in the thickness direction of the sample 1.

In order to acquire the three-dimensional image circle 2, it is necessary to turn the sample 1 upside down. FIG. 2 shows a method for obtaining the three-dimensional image circle 2 in the case of a conventional sample holder. In order to acquire the three-dimensional image circle 2, the tip portion (retainer) 3 of the sample holder 2 shown in the figure is removed from the sample holder 2 after the three-dimensional image circle 1 is acquired. Next, the retainer 3 is rotated 180 degrees and attached to the sample holder 2 again. The three-dimensional image circle 2 can be acquired by the above method.
(Example 2)
The high resolution tomography method of Example 2 is the same as that of Example 1. The sample holder 2 is different from the first embodiment. FIG. 3 is a schematic diagram of a sample holder having an automatic rotation mechanism. Reference numeral 2a denotes a sample holder having a rotation mechanism. A retainer 3 and a sample 1 are attached to the sample holder 2a. In this state, when the sample holder 2a is rotated 180 degrees, the sample 1 is just turned over. In the second embodiment, since the sample holder 2a rotates 180 degrees, it can be automatically rotated 180 degrees compared to the conventional method of turning the sample over, so that the sample can be turned over with good operability.

  The type and shape of the sample are not limited, but acrylonitrile / butadiene / styrene polymerization synthetic resin (ABS resin) was used as one of the general-purpose polymer materials. First, a sample section having a thickness of 1 μm was cut out from the ABS resin using an ultramicrotome and placed on a copper grid for TEM / STEM observation. Thereafter, the polybutadiene (PB) phase was metal-stained with the vapor of the osmium tetroxide solution, and an STEM image of the sample dyed using STEM was obtained. The three-dimensional image circle 1 was obtained by inclining at various angles and applying the CT method from the inclined STEM image series. In the same manner as in FIG. 1B, the sample was turned over, and the same region was obtained using a STEM tomography to obtain a three-dimensional image circle 2.

  FIG. 4 shows a STEM image of ABS resin with an inclination angle of 0 degree. FIG. 4A is a STEM image taken by normal STEM tomography, and FIG. 4B is a STEM image taken by turning the sample over and photographing the same region. It can be seen that FIGS. 4A and 4B are symmetrical images. The gray phase in the STEM image is the PB phase, and the white phase is a mixed (PA / PS) phase of polyacrylonitrile and polystyrene. Further, the small black particles are gold particles, and these gold particles are attached to the front and back surfaces of the sample. It can be seen that the gold particles on the back side of the sample indicated by the broken black circle in the STEM image with an inclination angle of 0 degrees are blurred, and the influence of beam broadening (beam expansion) can also be confirmed from the STEM image.

  FIG. 5 shows a reconstructed cross-sectional image. 5A is a cross section of the three-dimensional image circle 1, and FIG. 5B is a cross section of the three-dimensional image circle 2. 5A and 5B are cut out from the same cross section. The circular black phase in FIG. 5 is the PB phase, and the other gray phase (small circular phase inside the matrix and PB phase) is the PA / PS phase.

  Further, since the z-axis direction is the incident direction of the electron beam, in FIG. 5A, the electron beam is incident from the top to the bottom, and in FIG. 5B, the electron beam is incident from the bottom to the top. doing. A region surrounded by a broken black frame is a region in which an electron beam is incident about 0.6 μm from the sample surface. The boundary between the PB phase (black phase) and the matrix is also clear inside the broken black frame, and the presence of a small PA / PS phase (white phase) inside the PB phase can also be clearly confirmed.

  On the other hand, outside the broken black frame (area from about 0.6 μm from the sample surface to the back of the sample), the boundary between the PB phase and the matrix is unclear, and the presence of small PA / PS phase inside the PB phase is unclear or confirmed. There are some parts that cannot be done. From the reconstructed cross section, the effect of beam broadening increased with the distance of incidence of the electron beam, and a decrease in resolution was confirmed.

  Furthermore, in order to show the resolution | decomposability fall by the influence of beam broadening, the xy slice image which cut out the three-dimensional image by the xy plane is shown in FIG. FIG. 6A is an xy slice image of the three-dimensional image circle 1. An electron beam is incident from the top to the bottom of FIG. 6A, and an xy slice image is cut out every 100 nm from a position where the sample surface is set to 0 nm and enters 180 nm from the surface.

  FIG. 6B is an xy slice image of the three-dimensional image circle 2, and an electron beam is incident from the bottom to the top, contrary to FIG. 6A. Further, the adjacent xy slice images in FIGS. 6A and 6B have the same cutout position relationship. In FIG. 6A, the boundary between the small white PA / PS phase and the matrix and the PB phase inside the PB phase of the xy slice image from the front surface (upper diagram) to the rear surface (lower diagram) becomes unclear. You can see how it goes.

  In FIG. 6B, the same phenomenon was observed from the sample surface (bottom) to the back surface (top). Thus, it became clear that the spatial resolution decreases toward the bottom of the sample due to the influence of beam broadening. Therefore, it was decided to create a new three-dimensional image circle 3 by cutting out and synthesizing images from the sample surface of the three-dimensional image circle 1 and the three-dimensional image circle 2 at a position of about 500 nm (see FIG. 1 for the method).

  FIG. 7 shows a development view from a three-dimensional image. 7A is a development view of the three-dimensional image circle 1, FIG. 7B is a development view of the three-dimensional image circle 2, and FIG. 7C is an area of about 500 nm from the surface of the three-dimensional image circle 1 (a black frame area of a broken line). 3D image circle 1 ′ obtained by synthesizing a 3D image circle 1 ′ obtained by cutting out a region of about 500 nm (a dashed black frame region) from the surface of the 3D image circle 2). . In the xz slice images (reconstructed cross-sectional images) and yz slice images in FIGS. 7A and 7B, the resolution is lowered due to the influence of beam broadening in the z-axis direction, and the image is blurred. I can confirm. On the other hand, in FIG. 7C, by combining the regions where the influence of beam broadening in FIGS. 7A and 7B is small, the influence of beam broadening is suppressed in the z-axis direction and the spatial resolution is reduced. A high line is obtained.

As described above in detail, according to the present invention, a reduction in spatial resolution due to beam broadening in the sample thickness direction is reduced, and a highly quantitative three-dimensional image can be acquired.
Example 3
FIG. 8 is an explanatory diagram of another high-resolution tomography method according to the present invention. First, an inclined STEM image series is obtained in the same manner as in normal STEM tomography, and a reconstructed cross-sectional image circle 1 is obtained by applying the CT method. Next, the observed sample is turned over to obtain an inclined STEM image series for the same region as before, and a reconstructed cross-sectional image circle 2 is obtained by applying the CT method. Next, the reconstructed cross-sectional image circle 2 is rotated so as to be in the same direction as the reconstructed cross-sectional image circle 1.

  Next, the reconstructed cross-sectional image circle 1 is Fourier transformed to obtain a Fourier transform image circle 1. Next, the image obtained by rotating the reconstructed cross-sectional image circle 2 by 180 ° is Fourier transformed to obtain the Fourier transform image circle 2. Next, the Fourier transform image circle 3 is obtained by adding the Fourier transform image circle 1 and the Fourier transform image circle 2 together. The obtained Fourier transform image circle 3 can be subjected to inverse Fourier transform to obtain a reconstructed cross-sectional image circle 3. Once the reconstructed cross-sectional image circle 3 is obtained, it is easy to obtain a three-dimensional image using an existing technique.

  A reconstructed image having a uniform spatial resolution can be obtained by the above method, and a three-dimensional image having a high spatial resolution can be obtained by stacking all the reconstructed sectional images using this method. It becomes possible.

  Although there is no restriction | limiting in the kind and shape of a sample, the acrylonitrile butadiene styrene polymerization synthetic resin (ABS resin) which is one of the general purpose polymer materials this time was used. First, a sample section having a thickness of 1 μm was cut out from the ABS resin using an ultramicrotome and placed on a copper grid for TEM / STEM observation. Thereafter, the polybutadiene (PB) phase was metal-stained with the vapor of the osmium tetroxide solution, and an STEM image of the sample dyed using STEM was obtained.

  FIG. 9 is a view showing a STEM image of an ABS resin having an inclination angle of 0 °. (A) is a STEM image of a 1 μm thick ABS resin, and (b) is a STEM image of the same region taken by turning the sample over. The scale bar in the figure is 0.5 μm. It can be seen that (a) and (b) are symmetrical images. The gray phase in the STEM image is the PB phase, and the white phase is a mixed (PA / PS) phase of polyacrylonitrile and polystyrene. Further, the small black particles are gold particles, and these gold particles are attached to the front and back surfaces of the sample. It can be seen that the gold particles on the back surface of the sample indicated by the broken black circles in the STEM image with an inclination angle of 0 ° are blurred, and the blur of the image due to the influence of beam broadening is also apparent from the STEM image.

  FIG. 10 is a diagram showing a reconstructed cross-sectional image obtained by applying the inclined STEM image series CT method. This figure shows reconstructed cross-sectional images obtained by applying the CT method to a series of tilted STEM images obtained by tilting the sample at various angles. In (a), since the electron beam is transmitted from the top to the bottom with respect to the paper surface, the spatial resolution is reduced due to beam broadening at the bottom, and (b) is the electron beam from the bottom to the top with respect to the paper surface. Due to the transmission, the spatial resolution is reduced by beam broadening at the top.

  For example, in the white circle portion in FIG. 10, the boundary of each phase is clearer in (a), while the broken white circle portion in (b) shows smaller PA / PS phase particles inside the PB phase. Thus, the spatial resolution is not uniform in each reconstructed cross section. Therefore, in order to suppress the spatial resolution due to beam broadening, each reconstructed cross-sectional image was Fourier transformed to obtain a Fourier transformed image according to the procedure of the present invention.

  FIG. 11 is a diagram showing a Fourier transform image. 10A corresponds to the Fourier transform image of FIG. 10A, and FIG. 10B corresponds to the Fourier transform image of FIG. A Fourier transform image could be obtained by adding the two Fourier transform images in Fourier space (FIG. 12A). FIG. 12 is a diagram showing a Fourier transform image and a reconstructed cross-sectional image obtained by the present invention. (A) is a Fourier transform image, (b) is a reconstructed cross-sectional image after the final inverse Fourier transform.

By performing inverse Fourier transform on the Fourier transform image, a reconstructed cross-sectional image as shown in (b) could be obtained. In this reconstructed cross-sectional image, both the solid and broken white circles in (b) have clear phase boundaries and internal structures, and there is no decrease in spatial resolution in the vertical direction with respect to the paper surface. It is a reconstructed cross-sectional image with high uniform quantitativeness. According to this embodiment, the reconstructed cross-sectional images obtained by photographing from the front surface and the back surface of the sample are added in Fourier space, thereby reducing the spatial resolution caused by the effect of beam broadening in the sample thickness direction. This makes it possible to obtain a highly quantitative three-dimensional image.
Example 4
FIG. 13 is an explanatory diagram of another high-resolution tomography method according to the present invention. First, a tilted STEM image series is obtained in the same manner as in normal STEM tomography, and the reconstructed cross-sectional image circle 1 is obtained by applying the CT method. Next, the observed sample is turned over, and an inclined STEM image series is acquired again for the same region as before, and a reconstructed cross-sectional image circle 2 is obtained by applying the CT method.

  Then, the reconstructed sectional image circle 2 is rotated so as to be in the same direction as the reconstructed sectional image circle 1. Next, the reconstructed cross-sectional image circle 1 and the reconstructed cross-sectional image circle 2 are added in real space to obtain a reconstructed cross-sectional image circle 3. This embodiment is different from the embodiment 1 in that the images are added on the XY plane, whereas the images are added on the XZ plane.

  With the above method, a reconstructed cross-sectional image having a uniform spatial resolution can be obtained, and a three-dimensional image with a high spatial resolution can be obtained by stacking all reconstructed cross-sectional images using this method. .

  The type and shape of the sample are not limited, but acrylonitrile / butadiene / styrene polymerization synthetic resin (ABS resin) was used as one of the general-purpose polymer materials. First, a sample section having a thickness of 1 μm was cut out from the ABS resin using an ultramicrotome and placed on a copper grid for TEM / STEM observation. Thereafter, the polybutadiene (PB) phase was metal-stained with the vapor of the osmium tetroxide solution, and an STEM image of the sample dyed using STEM was obtained.

  FIG. 14 is a view showing a STEM image of an ABS resin having an inclination angle of 0 °. FIG. 14A is a STEM image photographed by normal STEM tomography, and FIG. 14B is a STEM image photographed in the same region with the sample turned over. It can be seen that (a) and (b) are symmetrical images. The gray phase in the STEM image is the PB phase, and the white phase is a mixed (PA / PS) phase of polyacrylonitrile and polystyrene. Further, the small black particles are gold particles, and these gold particles are attached to the front and back surfaces of the sample.

  It can be seen that the gold particles on the back surface of the sample indicated by the broken black circle in the STEM image at an inclination angle of 0 ° are blurred, and the blur of the image due to the effect of beam broadening is also apparent from the STEM image. FIG. 15 shows reconstructed cross-sectional images obtained by applying the CT method to the tilted STEM image series obtained by tilting the sample at various angles. In (a), since the electron beam is transmitted from the top to the bottom with respect to the paper surface, the spatial resolution is reduced due to beam broadening at the bottom, and (b) is the electron beam from the bottom to the top with respect to the paper surface. Since it is transmitted, the spatial resolution is reduced by beam broadening at the top.

  For example, the white circles in FIG. 15 (a) show clearer boundaries between the phases, while the dashed white circles show clearer PA / PS phase particles inside the PB phase (b). . Thus, the spatial resolution is not uniform in each reconstructed cross section. Therefore, in order to suppress the spatial resolution due to beam broadening, two reconstructed cross-sectional images shown in FIGS. 15A and 15B were added in real space according to the procedure of the present invention.

  FIG. 16 shows a reconstructed cross-sectional image obtained by the present invention. In this reconstructed cross-sectional image, both the solid and broken white circles in FIG. 16 have clear phase boundary portions and internal structures, and there is no decrease in the spatial resolution in the vertical direction with respect to the paper surface, and the spatial resolution is uniform. It can be seen that the reconstructed cross-sectional image is highly quantitative.

  As described above in detail, according to the present invention, a reduction in spatial resolution due to beam broadening in the specimen thickness direction is reduced, and a highly quantitative three-dimensional image can be acquired. In addition, a reconstructed cross-sectional image having a uniform spatial resolution can be obtained, and a three-dimensional image having a high spatial resolution can be obtained by stacking all reconstructed cross-sectional images using this method.

1 Sample 2 Sample holder 2a 'Sample holder 3 Retainer

Claims (7)

In a scanning transmission electron microscope, the sample is tilted to obtain a first three-dimensional image of the sample using a computed tomography method,
The sample is then turned over and the sample is tilted to obtain a second 3D image of the sample using a computed tomography method,
An image obtained by cutting out the upper half of the first three-dimensional image of the resulting sample, the synthetic 3-dimensional image of the sample by synthesizing the images obtained by cutting out the upper half of the second three-dimensional image of the sample obtain,
A method for acquiring a three-dimensional image of a sample using a tomography method, characterized in that it is configured as described above. In the scanning transmission electron microscope, a three-dimensional image acquisition means for obtaining a three-dimensional image of the sample is provided,
Obtaining a first three-dimensional image of the sample using the three-dimensional image obtaining means;
Next, the sample is turned over to obtain a second 3D image of the sample using the 3D image acquisition means,
An image obtained by cutting out upper half of the first three-dimensional image of the obtained sample, obtain a combined three-dimensional image of the sample by synthesizing the images obtained by cutting out the upper half of the second three-dimensional image,
An apparatus for acquiring a three-dimensional image of a sample using a tomography method, characterized in that it is configured as described above.   The apparatus for obtaining a three-dimensional image of a sample using the tomography method according to claim 2, further comprising a sample rotation mechanism for automatically turning over the sample. In a scanning transmission electron microscope, the sample is tilted to obtain a first reconstructed cross-sectional image of the sample using a computer tomography method,
The sample is then turned over and the sample is tilted to obtain a second reconstructed cross-sectional image of the sample using computed tomography,
Fourier transforming the first reconstructed cross-sectional image to obtain a first Fourier transform image,
A rotation process and a Fourier transform process are performed on the second reconstructed cross-sectional image to obtain a second Fourier transform image,
The first Fourier transform image and the second Fourier transform image are added to obtain a third Fourier transform image,
The third Fourier transform image is subjected to inverse Fourier transform to obtain a reconstructed sectional image.
A method for acquiring a three-dimensional image of a sample using a tomography method, characterized in that it is configured as described above. In the scanning transmission electron microscope, a reconstructed cross-sectional image acquisition means for obtaining a reconstructed cross-sectional image of the sample is provided,
A first reconstructed cross-sectional image of the sample is obtained using the reconstructed cross-sectional image acquisition means,
Next, the sample is turned over to obtain a second reconstructed cross-sectional image of the sample using the reconstructed cross-sectional image acquisition means,
A Fourier transform means for Fourier transforming the reconstructed cross-sectional image of the sample is provided,
Fourier transforming the first reconstructed cross-sectional image using the Fourier transform means to obtain a first Fourier transform image,
The second reconstructed cross-sectional image is subjected to rotation processing and Fourier transform processing using the Fourier transform means to obtain a second Fourier transform image,
Adding means for adding the first Fourier transform image and the second Fourier transform image to obtain a third Fourier transform image;
Inverse Fourier transform means for performing inverse Fourier transform on the third Fourier transform image that is the output of the adding means is provided,
The output of the inverse Fourier transform means is the final reconstructed cross-sectional image,
An apparatus for acquiring a three-dimensional image of a sample, characterized by being configured as described above. Obtain a first reconstructed cross-sectional image for a specific region of the sample by acquiring a tilted STEM image series and applying the CT method,
Next, the specific area again for Flip the specimen, and obtains the inclination STEM image series, give a second reconstructed cross-sectional image by applying the CT method,
Next, rotate the second reconstructed cross-sectional image so that it is in the same direction as the first reconstructed cross-sectional image,
Next, the first reconstructed cross-sectional image and the rotated second reconstructed cross-sectional image are added in real space to obtain a third reconstructed cross-sectional image.
A method for acquiring a three-dimensional image of a sample, characterized in that it is configured as described above. In the scanning transmission electron microscope, a reconstructed cross-sectional image acquisition means for obtaining a reconstructed cross-sectional image of the sample is provided,
A first reconstructed cross-sectional image is obtained for a specific region of the sample using the reconstructed cross-sectional image acquisition means,
Next, the sample is turned over to obtain a second reconstructed cross-sectional image for the specific region of the sample using the reconstructed cross-sectional image acquisition means,
Rotate the second reconstructed cross-sectional image to be in the same direction as the first reconstructed cross-sectional image,
Providing an adding means for adding the first reconstructed cross-sectional image and the second reconstructed cross-sectional image in real space;
Using the adding means, the first reconstructed cross-sectional image and the rotated second reconstructed cross-sectional image are added in real space to obtain a third reconstructed cross-sectional image;
An apparatus for acquiring a three-dimensional image of a sample, characterized by being configured as described above.