JP2022015158A - Scanning transmission electron microscope - Google Patents

Abstract

To provide a scanning transmission electron microscope, capable of detecting an electron beam transmitted through a sample using two detectors without moving the two detectors.SOLUTION: A scanning transmission electron microscope 100 includes: an electron source emitting electron beams; an irradiation lens system 11 that focuses electron beams and irradiates a sample with the focused electron beams; a first deflector 12 for scanning the sample with electron beams; a second deflector 15 deflecting electron beams transmitted through the sample S; a first detector 20 detecting electron beams transmitted through the sample S; and a second detector 30 detecting electron beams transmitted through the sample S. The second deflector 15 switches between a first state where electron beams are incident on the first detector 20 and a second state where electron beams are incident on the second detector 30.SELECTED DRAWING: Figure 3

Description

The present invention relates to a scanning transmission electron microscope.

The scanning transmission electron microscope may be equipped with a plurality of detectors in order to perform various analyzes. Examples of the detector mounted on the scanning transmission electron microscope include a bright-field STEM detector, a dark-field STEM detector, an energy-distributed X-ray detector, and an electron energy loss spectroscope.

For example, Patent Document 1 discloses a scanning transmission electron microscope equipped with a dark-field STEM detector and an electron energy loss spectroscope. The darkfield STEM detector is an annular detector that detects scattered waves scattered by the sample. The electron energy loss spectroscope is a detector arranged on the optical axis and detects transmitted waves transmitted through a sample. Therefore, in the scanning transmission electron microscope, the dark field STEM image and the EELS spectrum can be acquired at the same time by using the dark field STEM detector and the electron energy loss spectroscope.

Japanese Patent Application Laid-Open No. 2003-249186

As described above, the scanning transmission electron microscope can simultaneously acquire a dark field STEM image and an EELS spectrum. However, since both the bright-field STEM detector and the electron energy loss spectroscope are arranged on the optical axis, the bright-field STEM image and the EELS spectrum cannot be acquired at the same time.

Therefore, in order to obtain a bright-field STEM image and an EELS spectrum in the same region on a sample, for example, after acquiring a bright-field STEM image using a bright-field STEM detector, the bright-field STEM detector is placed on the optical axis. The EELS spectrum must be acquired using an electron energy loss spectroscope after retracting from.

One embodiment of the scanning transmission electron microscope according to the present invention is
An electron source that emits an electron beam and
An irradiation lens system that focuses the electron beam emitted from the electron source and irradiates the sample.
A first deflector for scanning the sample with an electron beam emitted from the electron source, and
A second deflector that deflects the electron beam that has passed through the sample,
The first detector that detects the electron beam that has passed through the sample, and
A second detector that detects the electron beam that has passed through the sample, and
Including
The second deflector switches between a first state in which the electron beam is incident on the first detector and a second state in which the electron beam is incident on the second detector.

In such a scanning transmission electron microscope, the electron beam transmitted through the sample can be detected by the first detector and the second detector without moving the first detector and the second detector.

The figure which shows the structure of the scanning transmission electron microscope which concerns on embodiment. The figure for demonstrating the operation of the 2nd deflector. The figure for demonstrating the operation of the 2nd deflector. The figure for demonstrating the scan of an electron probe. The graph which shows the scan signal for operating a 1st deflector. The graph which shows the deflection signal for operating the 2nd deflector. The figure for demonstrating the operation of the conventional scanning transmission electron microscope. The figure which shows the structure of the scanning transmission electron microscope which concerns on the 1st modification. The figure for demonstrating the operation of the 2nd deflector. The figure for demonstrating the scan of an electron probe. The graph which shows the scan signal for operating a 1st deflector. The graph which shows the deflection signal for operating the 2nd deflector. The graph which shows the deflection signal for operating the 2nd deflector of the scanning transmission electron microscope which concerns on the 2nd modification. The figure for demonstrating the scan of an electron probe. The graph which shows the scan signal for operating a 1st deflector. The graph which shows the deflection signal for operating the 2nd deflector. The graph which shows the scan signal for operating a 1st deflector. The graph which shows the deflection signal for operating the 2nd deflector.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

1. 1. Configuration of Scanning Transmission Electron Microscope First, a scanning transmission electron microscope according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a scanning transmission electron microscope 100 according to the present embodiment.

As shown in FIG. 1, the scanning transmission electron microscope 100 includes an electron source 10, an irradiation lens system 11, a first deflector 12, an imaging lens system 13, an EELS deflector 14, and a second deflector. It includes 15, a first detector 20, a second detector 30, a control unit 40, and a data processing unit 50.

The electron source 10 emits an electron beam. The electron source 10 is, for example, an electron gun that accelerates electrons emitted from a cathode by an anode and emits an electron beam.

The irradiation lens system 11 irradiates the sample S with the electron beam generated by the electron source 10. The irradiation lens system 11 focuses electron beams to form an electron probe. The irradiation lens system 11 includes, for example, a condenser lens and a forward magnetic field of an objective lens.

The first deflector 12 deflects an electron beam emitted from the electron source 10 and irradiated to the sample S. The first deflector 12 functions as a scanning deflector for scanning the sample S with the electron probe.

Although not shown, the scanning transmission electron microscope 100 includes a sample stage, and the sample S is positioned on the sample stage. The sample S is arranged between the irradiation lens system 11 and the imaging lens system 13. Specifically, the sample S is arranged between the front magnetic field of the objective lens and the rear magnetic field of the objective lens.

The imaging lens system 13 guides the electron beam (transmitted electron beam) transmitted through the sample S to the first detector 20 and the second detector 30. The imaging lens system 13 includes, for example, a rear magnetic field of an objective lens, an intermediate lens, a projection lens, and the like.

The EELS deflector 14 deflects the transmitted electron beam and guides it to the first detector 20. The EELS deflector 14 deflects a transmitted electron beam traveling along the optical axis L. The optical axis L is the optical axis of the optical system (irradiation lens system 11 and imaging lens system 13) constituting the scanning transmission electron microscope 100.

The second deflector 15 deflects the transmitted electron beam. The second deflector 15 is arranged in front of the first detector 20 and the second detector 30. The second deflector 15 deflects the transmitted electron beam traveling along the optical axis L. The second deflector 15 may be a magnetic field type deflector or an electrostatic deflector.

In the scanning transmission electron microscope 100, the second deflector 15 switches between a first state in which the transmitted electron beam is incident on the first detector 20 and a second state in which the transmitted electron beam is incident on the second detector 30. be able to.

The first detector 20 is, for example, an electron energy loss spectroscope. Here, when an electron incident on the sample S collides with an atom constituting the sample S, the electron that interacts with the electron in the crystal or the crystal lattice and loses a part of its energy and is scattered is called an inelastic scattered electron. .. The electron energy loss spectroscope disperses the energy of this inelastically scattered electron. As a result, an electron energy loss spectrum (hereinafter, also referred to as “EELS spectrum”) can be obtained. The first detector 20 is arranged on the optical axis L.

The second detector 30 is, for example, a bright field STEM detector. The bright-field STEM detector detects the electron beam transmitted through the sample S without being scattered and the electrons scattered at a small angle by the sample S among the transmitted electron beams. This makes it possible to obtain a bright-field STEM image. The second detector 30 is arranged at a position deviating from the optical axis L. That is, the second detector 30 is not arranged on the optical axis L.

Although not shown, the second detector 30 may be arranged on the optical axis L, and the first detector 20 may be arranged at a position deviated from the optical axis L.

The control unit 40 controls the first deflector 12 and the second deflector 15. The control unit 40 includes, for example, a CPU (Central Processing Unit) and a storage device (RAM (Random Access Memory), ROM (Read Only Memory), and the like). The control unit 40 performs various calculation processes and various control processes by executing a program stored in the storage device by the CPU. At least a part of the function of the control unit 40 may be realized by a dedicated circuit such as an ASIC (gate array or the like).

The data processing unit 50 generates an EELS spectrum at each measurement point on the sample S based on the detection result of the transmitted electron beam in the first detector 20. The data processing unit 50 generates, for example, an image showing the distribution of elements based on the EELS spectrum at each measurement point.

Further, the data processing unit 50 generates a bright-field STEM image based on the detection result of the transmitted electron beam in the second detector 30.

The data processing unit 50 includes, for example, a CPU and a storage device. The data processing unit 50 performs various calculation processes and various control processes by executing a program stored in the storage device by the CPU. At least a part of the functions of the data processing unit 50 may be realized by a dedicated circuit such as an ASIC (gate array or the like).

2. 2. Operation In the scanning transmission electron microscope 100, by operating the second deflector 15, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired almost at the same time. EELS spectrum mapping is a method of acquiring an EELS spectrum for each measurement point (each pixel) while scanning on the sample S with an electron probe.

2 and 3 are diagrams for explaining the operation of the second deflector 15. FIG. 2 shows the first state in which the transmitted electron beam is incident on the first detector 20, and FIG. 3 shows the second state in which the transmitted electron beam is incident on the second detector 30.

The scanning transmission electron microscope 100 has a first state in which the transmission electron beam shown in FIG. 2 is incident on the first detector 20 and a second state in which the transmission electron beam shown in FIG. 3 is incident on the second detector 30. Can be taken. In the scanning transmission electron microscope 100, the first state and the second state can be switched by the second deflector 15.

FIG. 4 is a diagram for explaining scanning of an electron probe. FIG. 5 is a graph showing scanning signals S1 (X) and S1 (Y) for operating the first deflector 12. The scanning signal S1 (X) is a scanning signal for moving the electron probe in the X direction, and the scanning signal S1 (Y) is a scanning signal for moving the electron probe in the Y direction. The horizontal axis T of the graph shown in FIG. 5 is time, and the vertical axis I is the signal strength.

First, the electron probe is moved in the + X direction (first direction) to draw a scanning line L1 (an example of the first scanning line). Next, the electron probe is moved in the −X direction (second direction) opposite to the + X direction, and the scanning line L2 (second scanning line) is drawn at the same position as the scanning line L1. That is, the start point of the scan line L1 is the end point of the scan line L2, and the end point of the scan line L1 is the start point of the scan line L2. After drawing the scanning line L2, the electron probe is moved in the + Y direction. By repeating this step, the sample S is scanned.

FIG. 6 is a graph showing a deflection signal S2 for operating the second deflector 15.

As shown in FIG. 6, while the first deflector 12 moves the electron probe in the + X direction and draws the scanning line L1, the second deflector 15 does not deflect the transmitted electron beam. Therefore, the scanning transmission electron microscope 100 is in the first state in which the transmission electron beam shown in FIG. 2 is incident on the first detector 20. While the first deflector 12 moves the electron probe in the −X direction to draw the scanning line L2, the second deflector 15 deflects the transmitted electron beam. Therefore, the scanning transmission electron microscope 100 is in the second state in which the transmission electron beam shown in FIG. 3 is incident on the second detector 30. Therefore, while the scanning line L1 is being drawn, the transmitted electron beam is detected by the first detector 20, and while the scanning line L2 is being drawn, the transmitted electron beam is detected by the second detector 30.

In the scanning transmission electron microscope 100, the time from when the first detector 20 detects the transmitted electron beam at an arbitrary position on the sample S until the second detector 30 detects the transmitted electron beam at the same place is The time from the start of drawing the scanning line L1 to the end of drawing the next scanning line L2 is t (see FIG. 6) or less. As described above, in the scanning transmission electron microscope 100, the data of the bright field STEM image and the data of the EELS spectrum can be acquired almost at the same time at each measurement point on the sample S.

3. 3. The processing control unit 40 moves the electron probe to the first deflector 12 in the + X direction to draw the scanning line L1, and moves the electron probe to the first deflector 12 in the −X direction to draw the scanning line L1. The process of drawing the scanning line L2 at the same position as the above is performed. Further, the control unit 40 is in the first state in which the transmitted electron beam is incident on the first detector 20 while the scanning line L1 is drawn, and the transmitted electron beam is drawn while the scanning line L2 is drawn. The process of operating the second deflector 15 is performed so that the second state is incident on the second detector 30.

Specifically, the control unit 40 outputs the scanning signal S1 (X) and the scanning signal S1 (Y) shown in FIG. 5 to the first deflector 12, and outputs the deflection signal S2 shown in FIG. 6 to the second deflector 15. Output to. As a result, as shown in FIG. 4, the electron probe moves in the + X direction and the scanning line L1 is drawn, the electron probe moves in the −X direction and the scanning line L2 is drawn, and then the electron probe moves in the + Y direction. The process of moving to is repeated until the entire measurement target area is scanned. Further, while the scanning line L1 is drawn, the transmitted electron beam is incident on the first detector 20, and while the scanning line L2 is drawn, the transmitted electron beam is incident on the second detector 30.

The data processing unit 50 acquires the detection result of the transmitted electron beam in the first detector 20 in synchronization with the scanning of the electron probe by the first deflector 12 and the deflection of the transmitted electron beam by the second deflector 15. The data processing unit 50 generates an EELS spectrum at each measurement point on the sample S based on the detection result of the transmitted electron beam in the acquired first detector 20.

Further, the data processing unit 50 acquires the detection result of the transmitted electron beam in the second detector 30 in synchronization with the scanning of the electron probe by the first deflector 12 and the deflection of the transmitted electron beam by the second deflector 15. .. The data processing unit 50 generates a bright-field STEM image based on the detection result of the transmitted electron beam in the acquired second detector 30.

Here, when the transmitted electron beam is detected by the first detector 20, the electron probe moves in the + X direction, and when the transmitted electron beam is detected by the second detector 30, the electron probe moves in the −X direction. Have moved to. Therefore, the information in the X direction is inverted between the EELS spectrum of each measurement point and the bright field STEM image. Therefore, the data processing unit 50 inverts the X-axis of the bright field STEM image, for example. Thereby, the position on the bright field STEM image and the position where the EELS spectrum is obtained can be matched.

The data processing unit 50 causes the display unit to display the generated EELS spectrum, an image showing the distribution of the elements generated from the EELS spectrum of each measurement point, and a bright-field STEM image.

4. The scanning transmission electron microscope 100 includes a second deflector 15 that deflects the transmitted electron beam, and the second deflector 15 includes a first state in which the transmitted electron beam is incident on the first detector 20 and a transmitted electron beam. Switches between the second state and the second state in which the electron is incident on the second detector 30. Therefore, in the scanning transmission electron microscope 100, the transmitted electron beam can be detected by the first detector 20 and the second detector 30 without moving the first detector 20 and the second detector 30. That is, in the scanning transmission electron microscope 100, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired without moving the first detector 20 and the second detector 30. Further, in the scanning transmission electron microscope 100, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired almost at the same time.

FIG. 7 is a diagram for explaining the operation of a conventional scanning transmission electron microscope.

As shown in FIG. 7, in the conventional scanning transmission electron microscope, both the electron energy loss spectroscope (first detector 20) and the bright field STEM detector (second detector 30) are arranged on the optical axis. It had been. Therefore, the bright-field STEM detector is configured to be movable by a moving mechanism (not shown), and when the electron energy loss spectroscope detects a transmitted electron beam, the bright-field STEM detector is retracted from the optical axis. Was there. It takes time to retract the bright-field STEM detector from the optical axis and to return it to the optical axis. Therefore, in the conventional scanning transmission electron microscope, when the bright-field STEM image is acquired and the EELS spectrum mapping is performed at the same location on the sample, the position on the bright-field STEM image and the EELS spectrum are affected by the drift of the sample. There was a shift in the position of the measurement point.

On the other hand, since the scanning transmission electron microscope 100 includes the second deflector 15 as described above, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired almost at the same time. Therefore, in the scanning transmission electron microscope 100, the influence of sample drift can be reduced, and the deviation between the position on the bright-field STEM image and the position of the measurement point of the EELS spectrum can be reduced. Further, since the bright field STEM image data and the EELS spectrum mapping data can be acquired in a short time, the electron beam irradiation amount to the sample S can be reduced, and the damage to the sample S can be reduced.

In the scanning transmission electron microscope 100, the control unit 40 moves the electron probe in the + X direction to draw the scanning line L1 on the first deflector 12, and then moves the electron probe in the −X direction to obtain the scanning line L1. The process of drawing the scanning line L2 at the same position and the first state in which the transmitted electron beam is incident on the first detector 20 while the scanning line L1 is drawn, and the transmission while the scanning line L2 is drawn. The process of operating the second deflector 15 so that the electron beam is in the second state of being incident on the second detector 30 is performed.

Therefore, in the scanning transmission electron microscope 100, the data of the bright field STEM image and the data of the EELS spectrum can be acquired almost at the same time at each measurement point on the sample S. Therefore, in the scanning transmission electron microscope 100, the deviation between the position on the bright field STEM image and the position of the measurement point of the EELS spectrum can be reduced.

In the above, the case where the first detector 20 is an electron energy loss spectroscope and the second detector 30 is a bright field STEM detector has been described, but the first detector 20 and the second detector 30 have been described. , Other detectors may be used. Further, the first detector 20 may be a bright-field STEM detector, and the second detector 30 may be an electron energy loss spectroscope.

5. Modifications The present invention is not limited to the above-described embodiment, and various modifications can be carried out within the scope of the gist of the present invention. Hereinafter, the points different from the above-mentioned example of the scanning transmission electron microscope 100 will be described, and the same points will be omitted.

5.1. First modification 5.1.1. Configuration of Scanning Transmission Electron Microscope FIG. 8 is a diagram showing the configuration of the scanning transmission electron microscope 102 according to the first modification. Hereinafter, in the scanning transmission electron microscope 102 according to the first modification shown in FIG. 8, the members having the same functions as the constituent members of the scanning transmission electron microscope 100 described above are designated by the same reference numerals, and detailed description thereof will be given. Omit.

As shown in FIG. 1, the scanning transmission electron microscope 100 described above includes a first detector 20 and a second detector 30. On the other hand, the scanning transmission electron microscope 102 includes a first detector 20, a second detector 30, and a third detector 32.

The third detector 32 detects the transmitted electron beam. The third detector 32 is, for example, a split type detector. In the divided detector, the detection surface is divided into a plurality of regions, and each divided region can independently detect an electron beam. A split detector can be used to measure the deflection of an electron beam due to an electromagnetic field in a sample (differential phase contrast imaging, DPC). Therefore, the scanning transmission electron microscope 102 can obtain a DPC image that visualizes the deflection of the electron beam due to the electromagnetic field in the sample. The third detector 32 is arranged at a position deviating from the optical axis L.

5.1.2. Operation FIG. 9 is a diagram for explaining the operation of the second deflector 15.

In the scanning transmission electron microscope 102, by operating the second deflector 15, the first state in which the transmitted electron beam shown in FIG. 2 is incident on the first detector 20 and the transmitted electron beam shown in FIG. 3 are detected in the second state. It is possible to switch between the second state incident on the device 30 and the third state in which the transmission electron beam shown in FIG. 9 is incident on the third detector 32.

FIG. 10 is a diagram for explaining scanning of an electron probe. FIG. 11 is a graph showing scanning signals S1 (X) and S1 (Y) for operating the first deflector 12.

First, the electron probe is moved in the + X direction to draw the scanning line L1. Next, the electron probe is moved in the −X direction opposite to the + X direction, and the scanning line L2 is drawn at the same position as the scanning line L1. Next, the electron probe is moved in the + X direction to draw a scanning line L3 (an example of a third scanning line) at the same position as the scanning line L2. After drawing the scanning line L3, the electron probe is moved in the + Y direction. By repeating this step, the sample S is scanned.

FIG. 12 is a graph showing a deflection signal S2 for operating the second deflector 15.

As shown in FIG. 12, while the first deflector 12 moves the electron probe in the + X direction and draws the scanning line L1, the second deflector 15 does not deflect the transmitted electron beam. Therefore, the scanning transmission electron microscope 102 is in the first state in which the transmission electron beam shown in FIG. 2 is incident on the first detector 20. While the first deflector 12 moves the electron probe in the −X direction to draw the scanning line L2, the second deflector 15 deflects the transmitted electron beam. Therefore, the scanning transmission electron microscope 102 is in the second state in which the transmission electron beam shown in FIG. 3 is incident on the second detector 30. While the first deflector 12 moves the electron probe in the + X direction to draw the scanning line L3, the second deflector 15 changes the transmitted electron beam. The amount of deflection of the transmitted electron beam by the second deflector 15 while drawing the scanning line L3 is larger than the amount of deflection of the transmitted electron beam by the second deflector 15 while drawing the scanning line L2. Therefore, the scanning transmission electron microscope 102 is in the third state in which the transmission electron beam shown in FIG. 9 is incident on the third detector 32.

Therefore, while the scanning line L3 is being drawn, the transmitted electron beam is detected by the third detector 32. Thereby, at each measurement point on the sample S, the data of the bright field STEM image, the data of the EELS spectrum, and the data of the DPC image can be acquired almost at the same time.

5.1.3. The processing control unit 40 moves the electron probe to the first deflector 12 in the + X direction to draw the scanning line L1, and moves the electron probe to the first deflector 12 in the −X direction to draw the scanning line L1. The process of drawing the scanning line L2 at the same position as the scanning line L2 and the process of moving the electron probe to the first deflector 12 in the + X direction and drawing the scanning line L3 at the same position as the scanning line L2 are performed. Further, the control unit 40 is in the first state in which the transmitted electron beam is incident on the first detector 20 while the scanning line L1 is drawn, and the transmitted electron beam is drawn while the scanning line L2 is drawn. While the second state is incident on the second detector 30 and the scanning line L3 is drawn, the second deflector 15 is operated so that the transmitted electron beam is incident on the third detector 32. ..

Specifically, the control unit 40 outputs the scanning signal S1 (X) and the scanning signal S1 (Y) shown in FIG. 11 to the first deflector 12, and outputs the deflection signal S2 shown in FIG. 12 to the second deflector 15. Output to. As a result, as shown in FIG. 10, the electron probe moves in the + X direction and the scanning line L1 is drawn, the electron probe moves in the −X direction and the scanning line L2 is drawn, and the electron probe moves in the + X direction. Then, the scanning line L3 is drawn, and then the electron probe repeatedly moves in the + Y direction. Further, while the scanning line L1 is drawn, the transmitted electron beam is incident on the first detector 20, and while the scanning line L2 is being drawn, the transmitted electron beam is incident on the second detector 30. While the scanning line L3 is drawn, the transmitted electron beam is incident on the third detector 32.

The data processing unit 50 generates an EELS spectrum at each measurement point on the sample S based on the detection result of the transmitted electron beam in the first detector 20, and is based on the detection result of the transmitted electron beam in the second detector 30. To generate a bright-field STEM image. Further, the data processing unit 50 acquires the detection result of the transmitted electron beam in the third detector 32 in synchronization with the scanning of the electron probe by the first deflector 12 and the deflection of the transmitted electron beam by the second deflector 15. .. The data processing unit 50 generates a DPC image based on the detection result of the transmitted electron beam in the acquired third detector 32.

The data processing unit 50 causes the display unit to display the generated EELS spectrum, an image showing the distribution of elements generated from the EELS spectrum of each measurement point, a bright-field STEM image, and a DPC image.

5.1.4. Action Effect In the scanning transmission electron microscope 102, the second deflector 15 has a first state in which the transmitted electron beam is incident on the first detector 20 and a second state in which the transmitted electron beam is incident on the second detector 30. The third state in which the electron beam is incident on the third detector 32 is switched. Therefore, in the scanning transmission electron microscope 102, the EELS spectrum mapping data, the bright field STEM image data, and the DPC image data are obtained without moving the first detector 20, the second detector 30, and the third detector 32. You can get it. Further, in the scanning transmission electron microscope 102, the data of EELS spectrum mapping, the data of the bright field STEM image, and the data of the DPC image can be acquired almost at the same time.

Although the case where the scanning transmission electron microscope 102 has three detectors has been described above, the scanning transmission electron microscope 102 may have four or more detectors. When the scanning transmission electron microscope 102 has four or more detectors, the same processing as in the case of having three detectors can be performed, and the same operation and effect can be obtained.

5.2. 2nd Modified Example FIG. 13 is a graph showing a deflection signal S2 for operating the second deflector 15 of the scanning transmission electron microscope according to the second modified example.

In the above-described embodiment, as shown in FIG. 6, the time for drawing the scanning line L1 and the time for drawing the scanning line L2 are equal. That is, the time for the first detector 20 to detect the transmitted electron beam and the time for the second detector 30 to detect the transmitted electron beam are equal. On the other hand, as shown in FIG. 13, the time for drawing the scanning line L1 and the time for drawing the scanning line L2 may be different. In the example shown in FIG. 13, the time for detecting the transmitted electron beam by the first detector 20 is longer than the time for detecting the transmitted electron beam by the second detector 30.

As described above, in the second modification, the time for detecting the transmitted electron beam is different for each detector, so that the time for detecting the transmitted electron beam can be appropriately adjusted for each detector according to the performance of the detector and the like. ..

5.3. Third variant example 53.1. Configuration of Scanning Transmission Electron Microscope The configuration of the scanning transmission electron microscope according to the third modification is the same as that of the scanning transmission electron microscope 100 shown in FIG. 1, and the description thereof will be omitted.

5.3.2. Operation FIG. 14 is a diagram for explaining scanning of an electron probe. FIG. 15 is a graph showing scanning signals S1 (X) and S1 (Y) for operating the first deflector 12.

As shown in FIG. 14, the electron probe is moved in the + X direction to draw the scanning line L1, the scanning line L1 is drawn, and then the electron probe is moved in the + Y direction repeatedly to scan on the sample S. .. By scanning the electron probe in this way, the electron probe sequentially irradiates each measurement point on the sample S. The measurement point corresponds to, for example, a pixel of a bright-field STEM image.

FIG. 16 is a graph showing a deflection signal S2 for operating the second deflector 15.

As shown in FIG. 16, when the electron probe sequentially irradiates each measurement point by the first deflector 12, the second deflector 15 switches between the first state and the second state at each measurement point. In the example shown in FIG. 16, at each measurement point, the transmitted electron beam is detected by the first detector 20 and then detected by the second detector 30.

At each measurement point, the time for the first state and the time for the second state are equal. That is, at each measurement point, the time during which the transmitted electron beam is detected by the first detector 20 and the time during which the transmitted electron beam is detected by the second detector 30 are equal.

5.3.3. The processing control unit 40 repeatedly moves the electron probe in the + X direction to the first deflector 12 to draw the scanning line L1, draws the scanning line L1, and then moves the electron probe in the + Y direction, and repeats each measurement. The points are sequentially irradiated with electron probes. Further, the control unit 40 performs a process of causing the second deflector 15 to switch between the first state and the second state at each measurement point on the sample S.

Specifically, the control unit 40 outputs the scanning signal S1 (X) and the scanning signal S1 (Y) shown in FIG. 15 to the first deflector 12, and the deflection signal S2 shown in FIG. 16 is output to the second deflector 15. Output to. As a result, the electron probe moves in the + X direction and the scanning line L1 is drawn, and then the electron probe moves in the + Y direction repeatedly, so that each measurement point is irradiated with the electron probe. Further, at each measurement point, the first state and the second state are switched. For example, the transmitted electron beam is incident on the first detector 20 and then on the second detector 30.

The data processing unit 50 generates an EELS spectrum at each measurement point on the sample S based on the detection result of the transmitted electron beam in the first detector 20, and is based on the detection result of the transmitted electron beam in the second detector 30. To generate a bright-field STEM image.

5.3.4. In the transmission scanning electron microscope according to the third modification, the control unit 40 causes the first deflector 12 to sequentially irradiate each measurement point on the sample S with an electron beam, and the second deflector 15 to receive an electron beam. At each measurement point on the sample S, a process of switching between the first state and the second state is performed. Therefore, in the scanning transmission electron microscope 102, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired without moving the first detector 20 and the second detector 30. Further, in the scanning transmission electron microscope according to the third modification, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired almost at the same time.

In the above, as shown in FIG. 16, the case where the transmitted electron beam is incident on the first detector 20 and then incident on the second detector 30 at each measurement point has been described. , The transmitted electron beam may be incident on the second detector 30 and then incident on the first detector 20.

Further, in the above, at each measurement point, the time for the transmitted electron beam to be incident on the first detector 20 and the time for the transmitted electron beam to be incident on the second detector 30 were equal, but the transmitted electron beam was the first detector. The time for incident on the 20 and the time for the transmitted electron beam to be incident on the second detector 30 may be different.

Further, although the case where the scanning transmission electron microscope includes two detectors has been described above, the case where the scanning transmission electron microscope includes three or more detectors is also applicable. For example, when the scanning transmission electron microscope includes three detectors as shown in FIG. 8, the first state, the second state, and the third state may be switched at each measurement point.

5.4. Fourth modified example 5.4.1. Configuration of Scanning Transmission Electron Microscope The configuration of the scanning transmission electron microscope according to the fourth modification is the same as that of the scanning transmission electron microscope 100 shown in FIG. 1, and the description thereof will be omitted.

5.4.2. Operation FIG. 17 is a graph showing scanning signals S1 (X) and S1 (Y) for operating the first deflector 12.

As shown in FIG. 17, first, the electron probe is moved in the + X direction to draw the scanning line L1, the scanning line L1 is drawn, and then the electron probe is moved in the + Y direction repeatedly to move the electron probe in the + Y direction on the sample S. Scan. As a result, the measurement target area on the sample S is scanned.

Next, the electron probe is moved in the + X direction again to draw the scanning line L1, the scanning line L1 is drawn, and then the electron probe is moved in the + Y direction repeatedly to scan on the sample S. As a result, the measurement target area on the sample S is scanned again.

FIG. 18 is a graph showing a deflection signal S2 for operating the second deflector 15.

As shown in FIG. 18, while the first deflector 12 scans the area to be measured for the first time, the second deflector 15 detects the transmitted electron beam in the first detector 20. Next, the transmitted electron beam is detected by the second detector 30 by the second deflector 15 while the first deflector 12 scans the measurement target area for the second time. For example, the time required for the first scan of the measurement target area and the time required for the second scan of the measurement target area are equal.

5.4.3. The processing control unit 40 performs processing for causing the first deflector 12 to scan the measurement target region on the sample S with an electron probe and to operate the second deflector 15 so as to be in the first state. Further, the control unit 40 causes the first deflector 12 to scan the measurement target area with the electronic probe after the process of operating the second deflector 15 so as to be in the first state, and to be in the second state. The process of operating the second deflector 15 is performed.

Specifically, the control unit 40 outputs the scanning signal S1 (X) and the scanning signal S1 (Y) shown in FIG. 17 to the first deflector 12, and the deflection signal S2 shown in FIG. 18 is output to the second deflector 15. Output to.
As a result, the measurement target area is scanned twice, the transmitted electron beam is detected by the first detector 20 in the first scan of the measurement target area, and the transmitted electron beam is detected in the second scan of the measurement target area. Is detected by the second detector 30.

5.4.4. In the transmission scanning electron microscope according to the fourth modification, the control unit 40 causes the first deflector 12 to scan the measurement target region on the sample S with the electron probe, and the second state is set to the first state. After the process of operating the deflector 15 and the process of operating the second deflector 15 so as to be in the first state, the first deflector 12 is made to scan the measurement target area with an electron probe, and the second state is obtained. The process of operating the second deflector 15 so as to be performed is performed.

As described above, in the scanning transmission electron microscope according to the fourth modification, the data of the bright field STEM image and the data of the EELS spectrum mapping can be acquired without moving the first detector 20 and the second detector 30. Further, in the scanning transmission electron microscope according to the fourth modification, for example, the bright field STEM image data and the EELS spectrum mapping data are obtained in a shorter time than when the first detector 20 and the second detector 30 are moved. Can be obtained.

In the above, as shown in FIG. 18, the transmitted electron beam is incident on the first detector 20 in the first scanning of the measurement target area, and the transmitted electron beam is detected in the second detection in the second scanning of the measurement target area. The case of being incident on the device 30 has been described, but the transmitted electron beam is incident on the second detector 30 in the first scan of the measurement target area, and the transmitted electron beam is first detected in the second scan of the measurement target area. It may be incident on the vessel 20.

Further, in the above, the case where the time required for the first scan of the measurement target area and the time required for the second scan of the measurement target area are equal has been described, but the time required for the first scan of the measurement target area and the second time are described. The time required for scanning the measurement target area may be different.

Further, although the case where the scanning transmission electron microscope includes two detectors has been described above, the case where the scanning transmission electron microscope includes three or more detectors is also applicable. For example, as shown in FIG. 8, when the scanning transmission electron microscope includes three detectors, the measurement target area is scanned three times, and the transmission electron beam is incident on the first detector 20 in the first scan of the measurement target area. Then, the transmitted electron beam may be incident on the second detector 30 in the second scan of the measurement target area, and the transmitted electron beam may be incident on the third detector 32 in the third scan of the measurement target area.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the present invention includes substantially the same configuration as that described in the embodiments. Substantially the same configuration is, for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect. The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. Further, the present invention includes a configuration having the same action and effect as the configuration described in the embodiment or a configuration capable of achieving the same object. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10 ... electron source, 11 ... irradiation lens system, 12 ... first deflector, 13 ... imaging lens system, 14 ... EELS deflector, 15 ... second deflector, 20 ... first detector, 30 ... second Detector, 32 ... Third detector, 40 ... Control unit, 50 ... Data processing unit, 100 ... Scanning transmission electron microscope, 102 ... Scanning transmission electron microscope

Claims (6)

An electron source that emits an electron beam and
An irradiation lens system that focuses the electron beam emitted from the electron source and irradiates the sample.
A first deflector for scanning the sample with an electron beam emitted from the electron source, and
A second deflector that deflects the electron beam that has passed through the sample,
The first detector that detects the electron beam that has passed through the sample, and
A second detector that detects the electron beam that has passed through the sample, and
Including
The second deflector is a scanning transmission electron microscope that switches between a first state in which an electron beam is incident on the first detector and a second state in which an electron beam is incident on the second detector. In claim 1,
A control unit for controlling the first deflector and the second deflector is included.
The control unit
The process of moving the electron beam to the first deflector in the first direction and drawing the first scanning line,
A process of moving an electron beam to the first deflector in a second direction opposite to the first direction and drawing a second scanning line at the same position as the first scanning line.
The process of operating the second deflector so that the first state is reached while the first scanning line is drawn and the second state is reached while the second scanning line is drawn.
A scanning transmission electron microscope. In claim 1,
A control unit for controlling the first deflector and the second deflector is included.
The control unit
A process of irradiating the first deflector with an electron beam at each measurement point on the sample in order,
A process of causing the second deflector to switch between the first state and the second state at each measurement point on the sample.
A scanning transmission electron microscope. In claim 1,
A control unit for controlling the first deflector and the second deflector is included.
The control unit
The process of causing the first deflector to scan the measurement target area on the sample with an electron beam and operating the second deflector so as to be in the first state.
After the process of operating the second deflector so as to be in the first state, the first deflector is made to scan the measurement target area with an electron beam, and the second deflector is brought into the second state. The process of operating the deflector and
A scanning transmission electron microscope. In any one of claims 1 to 4,
The first detector is an electron energy loss spectroscope.
The second detector is a scanning transmission electron microscope, which is a bright field detector. In any one of claims 1 to 5,
It includes a third detector that detects the electron beam that has passed through the sample.
The second deflector is a scanning transmission electron microscope that switches between the first state, the second state, and the third state in which an electron beam is incident on the third detector.

Images