JP6783071B2 - Charged particle beam device - Google Patents

Description

The present invention relates to a charged particle beam device.

A transmission electron microscope (hereinafter referred to as TEM) is a device for observing a transmission image generated by an electron beam passing through a sample. One of the observation methods is a method using a fluorescent plate. In this case, the TEM forms an image of the electron beam that has passed through the sample on the fluorescent screen, and observes the transmission image of the sample on the fluorescent plate through the window of the apparatus. This observation can be made in real time (ie, in real time).

As an observation method, there is also a method that does not use a fluorescent plate. In this case, the TEM directly detects the image of the electron beam transmitted through the sample using a photographing device such as a television camera, and sends the image signal of the detected transmission image to a display device connected to the outside of the device for display. .. In this case, the operator observes the transmission image displayed on the display device. However, this observation method requires time for image processing depending on the device configuration, and there is a possibility that a time delay may occur instead of real time.

Normally, the TEM control device is installed at a place away from the main body of the device, and the operator controls the operation of the TEM from the place where the control device is located. Therefore, the display device that displays the transmission image is installed at the place where the control device is installed so that the operator can easily observe it.

Japanese Unexamined Patent Publication No. 2008-181786

When observing a sample using a TEM, it is necessary to adjust the axis before observing the sample. Axis adjustment includes mechanical axis adjustment and electromagnetic axis adjustment. In mechanical axis adjustment, the optical axis is adjusted by physically moving the mirror body or the like. In the electromagnetic axis adjustment, the optical axis is adjusted by changing the current value of the lens, coil, or the like. The operator does not perform the mechanical axis adjustment, but the operator may perform the electromagnetic axis adjustment.

The electromagnetic axis adjustment performed by the operator includes current axis center adjustment, voltage axis center adjustment, beam deflection fulcrum adjustment, and focus adjustment. Of these, the current axis center adjustment, the voltage axis center adjustment, and the beam deflection fulcrum adjustment are performed regularly. These axis adjustments are visually performed by the operator. Therefore, the adjustment accuracy and the adjustment time may vary. In particular, the adjustment accuracy of the axis adjustment affects the sample observation, so that a high adjustment accuracy is required.

In order to solve the above problems, the present invention adopts, for example, the configuration described in the claims. The present specification includes a plurality of means for solving the above problems. For example, "a photographing device for photographing an image of a sample generated by irradiation with a charged particle beam and a deflection for deflecting the charged particle beam". A charged particle beam having a coil, a magnetic field lens for focusing the charged particle beam, a control device for controlling the deflection coil and the magnetic field lens, and an interface unit for displaying information on electromagnetic axis adjustment of the charged particle beam. It is a device.

According to the present invention, the operator can perform the electromagnetic axis adjustment with reference to the information displayed as the adjustment index, and can reduce the variation in the adjustment accuracy and the adjustment time. Issues, configurations and effects other than those described above will be clarified by the following description of embodiments.

The figure which shows the structural example of TEM which concerns on Example. The figure which shows an example of the operation screen used at the time of adjusting the center of a current axis. The flowchart which shows the example of the processing procedure executed at the time of the current axis center adjustment. The figure which shows an example of the observation image acquired by TEM. A flowchart showing the detailed contents of the screen update process S109. The figure which shows an example of the operation screen used at the time of adjusting the center of a voltage axis. The figure which shows an example of the operation screen used at the time of adjusting a beam deflection fulcrum. The flowchart which shows the example of the processing procedure executed at the time of the beam deflection fulcrum adjustment. The figure which shows an example of the observation image acquired at the time of adjusting a beam deflection fulcrum. The figure which shows an example of the operation screen used at the time of focus adjustment. A flowchart showing an example of a processing procedure executed at the time of focus adjustment.

Hereinafter, examples of the present invention will be described with reference to the drawings. The present invention is not limited to the examples described later, and various modifications can be made within the scope of the technical idea.

(1) Example 1
(1-1) Device Configuration Figure 1 shows an example of a TEM configuration. The electron beam emitted from the electron gun 1 and accelerated is converged by the irradiation system lens 2 and then deflected by the first deflection coil 3 and the second deflection coil 4. Further, the electron beam is imaged on the sample 6 mounted on the sample table 7 by the objective lens (front magnetic field) 5. The electron beam generator 12 controls the energy of the electron beam by adjusting the voltage applied to the electron gun 1. The electron beam irradiation system for irradiating the sample 6 with an electron beam is housed inside the main body of the apparatus shown by the broken line. The inside of the main body of the apparatus is kept in a vacuum by the vacuum exhaust pump 16.

The electron beam transmitted through the sample 6 is magnified by the imaging system lens 8 and imaged on the fluorescent screen 11. As a result, a fluorescent plate surface image corresponding to the sample transmission image appears on the fluorescent plate 11. The fluorescent plate surface image is taken by a camera (first imaging device) 9 for photographing the fluorescent plate. The camera 9 outputs an image signal that hits the surface image of the fluorescent screen. The TEM of this embodiment also corresponds to an observation method that does not use the fluorescent plate 11. When the observation method is used, the fluorescent plate driving device 15 retracts the fluorescent plate 11 from the optical axis of the electron beam, and the electron beam transmitted through the sample 6 is directly incident on the photographing surface of the camera (second imaging device) 10. As a result, the camera 10 outputs an image signal that hits the sample transmission image.

The image shooting magnification can be changed by controlling the electron beam adjusting device 13. The imaging field of view can be adjusted by moving the position of the sample table 7 by the sample moving device 14. The electron beam generator 12, the electron beam adjusting device 13, the sample moving device 14, the fluorescent plate driving device 15, and the vacuum exhaust pump 16 are all provided on the device main body side.

The computer 17 surrounded by a broken line includes a central arithmetic unit 17a, an image display memory 17b, an input / output interface 17c, image memories 17d and 17e, a program storage memory 17f, and a data storage memory 17g. The central arithmetic unit 17a executes a program stored in the program storage memory 17f and provides various functions. For example, the central calculation unit 17a temporarily stores the image signal received from the camera 9 or 10 in the image memory 17d. The image signal here is a fluorescent screen image or a sample transmission image. When the image signal is already stored in the image memory 17d, the central calculation unit 17a temporarily stores the image signal in the image storage memory 17e. When the image signal is already stored in both the image memory 17d and the image storage memory 17e, the central calculation unit 17a alternately deletes the stored image signal to secure the storage area.

When displaying the sample transmission image on the screen, the central calculation unit 17a stores the image signal read from the image memory 17d (or 17e) in the image display memory 17b, and then displays the display device (interface unit) through the input / output interface 17c. ) Displayed at 18. Various data related to the TEM, data calculated by the central calculation unit 17a by calculation, and the like are stored in the data storage memory 17g. The central arithmetic unit 17a controls the operations of the electron beam generator 12, the electron beam adjusting device 13, the sample moving device 14, the fluorescent screen driving device 15, and the vacuum exhaust pump 16 by executing the program stored in the program storage memory 17f. To do.

(1-2) Current axis center adjustment operation (a) Outline of processing At the time of current axis center adjustment, the operator accesses the central calculation unit 17a through the operation of the operation panel and instructs the execution of the corresponding program. The central arithmetic unit 17a controls the electron beam adjusting device 13 and keeps changing the current value of the objective lens 5 slightly in the positive and negative directions. Due to the change in the current value of the objective lens 5, the fluorescent plate image displayed on the fluorescent screen 11 or the sample transmission image observed by the camera 10 is rotated and simultaneously enlarged or reduced.

Next, the central calculation unit 17a temporarily stores the image signal received from the camera 9 or 10 in the image memory 17d or 17e, and stores the image signal in the image display memory 17b and displays it on the display device 18. To do.

FIG. 2 shows an example of an operation screen displayed when adjusting the center of the current axis. The central calculation unit 17a updates all or part of the information displayed on the interface screen 19 and the adjustment information display screen 23 in real time. As a result, the operator can confirm the adjustment result in real time and can improve the work efficiency.

The interface screen 19 displays two images 19A or 19B taken before and after changing the current value. The image 19A corresponds to the image before the change of the current value, and the image 19B corresponds to the image after the change of the current value. Both are images taken by the same camera 9 or 10. That is, images 19A and 19B are both fluorescent screen images or sample transmission images. FIG. 2 shows how the image 19B is rotated with respect to the image 19A and simultaneously enlarged due to the change in the current value. Of course, the image 19B may be reduced with respect to the image 19A.

The central calculation unit 17a executes an image processing program stored in the program storage memory 17f, and calculates a conversion characteristic inherent in the change from the image 19A to the image 19B and an adjustment amount for canceling the conversion characteristic. The central calculation unit 17a displays the rotation center position 20, the rotation center movement direction 21, and the movement amount 22 on the interface screen 19 as calculation results. The rotation center position 20 indicates the center position of the rotation conversion that occurs between the images as the current value changes. The rotation center moving direction 21 indicates a direction in which the rotation center should be moved at the time of adjustment. The movement amount 22 indicates an amount to move the rotation center position 20 at the time of adjustment. The interface screen 19 displays a pixel value as the movement amount 22. The pixel value corresponds to the on-screen length of a characteristic figure described later.

The central calculation unit 17a calculates adjustment information based on information such as the rotation center position 20, the rotation center movement direction 21, and the movement amount 22, and presents the calculation result (adjustment index) on the adjustment information display screen 23. In the case of FIG. 2, the adjustment information display screen 23 is arranged on the right side of the interface screen 19. The adjustment procedure 24, the simplified light beam diagram 25, the adjustment target name 26, the pseudo knobs 27A and 27B, the knob rotation direction 28, and the adjustment amount 29 are displayed on the adjustment information display screen 23. Incidentally, the pseudo knob 27A is an adjustment knob for the X axis, and the pseudo knob 27B is an adjustment knob for the Y axis. The symbol "BT" representing the adjustment target name 26 represents the deflection coils 3 and 4.

Each time the set of images 19A and 19B displayed on the interface screen 19 is updated, the central calculation unit 17a executes the image processing program, and each time, the rotation center position 20, the rotation center movement direction 21, and the movement amount are executed. The display contents of 22 and the adjustment information display screen 23 are updated. The operator refers to the information presented on the interface screen 19 and the adjustment information display screen 23, and adjusts the center of the current axis. As described above, in this embodiment, the operator can perform the adjustment work based on specific numerical values and objective information, and can reduce the adjustment variation and the adjustment time difference between the operators.

(B) Details of processing operation FIG. 3 shows an example of a processing procedure of an image processing program executed by the central calculation unit 17a at the time of adjusting the center of the current axis. The image processing program targets the image signal stored in the image memory 17d (or 17e) as a processing target, and executes calculation of information to be displayed on the interface screen 19 and the adjustment information display screen 23.

First, the central calculation unit 17a acquires an image signal from the image memory 17d (or 17e) (S101). As described above, the image signal is a fluorescent plate surface image taken by the camera 9 or a sample transmission image taken by the camera 10, and is not both. Next, the central calculation unit 17a acquires the current current value of the objective lens 5 from the electron beam adjusting device 13 and confirms whether or not there is a change (S102). When the current current value of the objective lens 5 is different from the current value when the image signal read in S101 is captured, the central arithmetic unit 17a acquires the image signal from another image memory 17e (or 17d) (S103). ). When the current current value of the objective lens 5 is the same as the current value when the image signal read in S101 is captured, the central calculation unit 17a repeats the confirmation process of S102 until the change is confirmed.

The central calculation unit 17a processes the image signal acquired in S101 and the image signal acquired in S103, and calculates the amount of rotation θ between the two images (S104). These two images are images taken by the same camera. The procedure for calculating the rotation amount θ will be described below. First, the central calculation unit 17a extracts a characteristic region from the two acquired images. The characteristic area is, for example, a scratch or stain on the sample.

FIG. 4 shows an example of a characteristic region. The characteristic region 101 represents a state in which the characteristic region 100 in the observation image is rotated and translated due to a change in the current value of the objective lens 5. The characteristic region includes, for example, a SIFT (Scale Invariant Feature Transform) feature quantity. The SIFT feature amount can be extracted by, for example, the following method. First, feature points are detected from the image. Feature points are detected, for example, from changes in images smoothed by Gaussian filters having different smoothness. Images with different resolutions are created and smoothed with a Gaussian filter to eliminate the effects of scaling. Next, the SIFT feature amount is generated from the detected feature points. For the SIFT feature amount, the direction in which the brightness change around the feature point is the largest is examined.

A 128-dimensional vector is obtained by setting a 4 × 4 block centered on the feature point based on the direction of the feature point and expressing the change in brightness for each block in eight directions. The 128-dimensional vector is normalized to length 1 and used as the SIFT feature quantity for one feature point. Algorithms are provided by general image processing libraries for SIFT features, and they may be used. Since the SIFT feature amount handles a 128-dimensional vector, it is possible to make the SIFT feature amount of the image before the change correspond to the image of the SIFT feature amount after the change with respect to the image changed by moving, rotating, enlarging or reducing. it can.

Next, the central calculation unit 17a obtains a homography matrix by using the coordinates of the characteristic region extracted from the two images. The homography matrix represents a two-dimensional projective transformation. The homography matrix can be easily calculated by using a general image processing library. Equation 1 shows the general formula of the homography matrix obtained from the set of feature point coordinates corresponding to the two images.

Here, sx is the enlargement ratio in the X direction, and sy is the enlargement ratio in the Y direction. θ is the rotation angle, e is the amount of movement in the X direction, and f is the amount of movement in the Y direction. Note that * is a multiplier.

Next, the central calculation unit 17a obtains the rotation amount θ using the homography matrix. Equation 2 shows the calculation equation.

After that, the central calculation unit 17a calculates the enlargement ratio or reduction ratio of the characteristic region from the two images (S105). The magnification or reduction ratio can also be determined using a homography matrix. The calculation formula is shown in Equation 3.

After that, the central calculation unit 17a calculates the rotation center coordinates of the characteristic region from the two images (S106). The coordinates of the center of rotation can also be calculated from the homography matrix. The calculation formula is shown in Equation 4.

After that, the central calculation unit 17a calculates the distance from the obtained rotation center position to the center position of the image (S107). The calculation formula is shown in Equation 5.

Next, the central calculation unit 17a obtains a necessary adjustment value based on the coordinates of the center of rotation and the distance to the center position of the image (S108). In order to obtain the adjustment value, the central calculation unit 17a obtains the inclination angle of the electron beam with respect to the adjustment parameter as a calibration value. The calibration value is, for example, a movement vector (bx, by) of the beam spot per 1 mA of the current value. Equation 6 shows an example of the calibration value.

Next, the central calculation unit 17a calculates the current value of the tilting coil for adjusting the center of rotation to the center of the observation screen by using the parameter obtained in S108. The calculation formula is shown in Equation 7.

After that, the central calculation unit 17a displays the results calculated in S104 to S108 on the interface screen 19 and the adjustment information display screen 23 (S109). Specifically, the adjustment procedure 24, the simple light ray diagram 25, the adjustment target name 26, the pseudo knobs 27A and 27B, the knob rotation direction 28, and the adjustment amount 29 are displayed.

FIG. 5 shows the detailed contents of the screen update process S109. The screen update process 109 is a process for displaying the movement amount and the rotation amount calculated by the central calculation unit 17a on the interface screen 19 and the adjustment information display screen 23. When the screen update process S109 is executed, the central calculation unit 17a acquires the calculated value (that is, the calculation result) from the data storage memory 17g (FIG. 1) (S201).

Next, the central calculation unit 17a draws two images 19A and 19B taken before and after the change of the current and a marker representing the rotation center position 20 thereof on the interface screen 19 based on the acquired result ( S202). After drawing the marker, the central calculation unit 17a draws the movement amount 22 on the interface screen 19 (S203), and further draws the rotation center movement direction 21 (S204).

Next, the central calculation unit 17a draws the adjustment procedure 24 on the adjustment information display screen 23 (S205). The adjustment procedure 24 includes, for example, "1. Display the observation screen", "2. Increase the power supply voltage by 100V", "3. Check the amount of change in the observation image displayed on the observation screen", "4. "Check the adjustment target knob and adjustment amount on the adjustment information display screen", "5. Change the adjustment target knob by the amount displayed on the adjustment information display screen", "6. Reduce the power supply voltage by 100V", " It is a message such as "7. Adjustment completed".

After displaying the adjustment procedure 24, the central calculation unit 17a draws a simple ray diagram 25 corresponding to the adjustment content (S206). In the simple light beam FIG. 25, for example, the positional relationship of both or one of the magnetic field lens (irradiation system lens 2, objective lens 5, imaging system lens, etc.) and deflection coils 3 and 4 to be adjusted is represented by symbols or figures. , The trajectory of the electron beam passing through the magnetic field lens and / or the deflection coil is represented.

After that, the central calculation unit 17a displays a schematic diagram of the adjustment knobs (pseudo knobs 27A and 27B in the case of FIG. 2) corresponding to the adjustment target name 26 at the lower part of the adjustment information display screen 23 (S207). Finally, the central calculation unit 17a draws the adjustment amount 29 and the adjustment direction (in the case of FIG. 2, the knob rotation direction 28) on the upper part of the pseudo knobs (both or one of the pseudo knobs 27A and 27B) that need to be adjusted. (S208). The adjustment amount 29 is a current value or a value corresponding to the current value used for controlling the magnetic field lens and the deflection coils 3 and 4. The value corresponding to the current value is, for example, the minimum unit when an analog value called a digit is converted into a digital value. The processing procedure shown in FIG. 5 is an example, and the execution order of each step is arbitrary.

(1-3) Effect of Example As described above, the TEM (Fig. 1) in this example supports various changes and adjustment work that occur before and after manual adjustment in the electromagnetic axis adjustment work by the operator. The information is calculated and displayed on the interface screen 19 and the adjustment information display screen 23. Therefore, the operator can perform the axis adjustment work with reference to an appropriate adjustment procedure and adjustment amount, and can reduce both the adjustment accuracy and the variation in the adjustment time difference.

(2) Example 2
(2-1) Device Configuration In this embodiment as well, the TEM having the configuration shown in FIG. 1 is used. In this embodiment, the operation when the operator adjusts the voltage axis center of the TEM will be described.

(2-2) Voltage axis center adjustment operation The operator also accesses the central calculation unit 17a through the operation of the operation panel and instructs the execution of the corresponding program during the voltage axis center adjustment operation. The central arithmetic unit 17a controls the electron beam generator 12 and keeps changing the voltage applied to the electron gun 1 alternately in the positive and negative directions. When the voltage value applied to the electron gun 1 changes, the fluorescent plate image displayed on the fluorescent plate 11 or the sample transmission image observed by the camera 10 is enlarged or reduced according to the change in the current value of the objective lens 5.

Next, the central calculation unit 17a temporarily stores the image signal received from the camera 9 or the camera 10 in the image memory 17d or 17e, stores the image signal in the image display memory 17b, and stores the image signal in the display device 18. indicate.

FIG. 6 shows an example of the interface screen 31 and the adjustment information display screen 35 displayed when the center of the voltage axis is adjusted. On the interface screen 31, two images 30A and 30B taken before and after changing the voltage value are displayed. In this embodiment, the image 30A corresponds to the image before the change in the voltage value, and the image 30B corresponds to the image after the change in the voltage value. Both are images taken by the same camera 9 or 10. That is, the images 30A and 30B are both fluorescent plate images or sample transmission images. FIG. 6 shows how the image 30B is enlarged with respect to the image 30A due to the change in the voltage value. Of course, the image 30B may be reduced with respect to the image 30A.

The central calculation unit 17a executes an image processing program stored in the program storage memory 17f, and calculates a conversion characteristic that causes a change from the image 30A to the image 30B and an adjustment amount for canceling the conversion characteristic. As a calculation result, the central calculation unit 17a displays the enlargement / reduction center position 32, the enlargement / reduction center movement direction 33, and the movement amount 34 on the interface screen 31. The enlargement / reduction center position 32 indicates the center position of the enlargement / reduction conversion that occurs between the images as the voltage value changes. The enlargement / reduction center movement direction 33 indicates a direction in which the enlargement / reduction center should be moved during adjustment. The movement amount 34 indicates an amount to be moved at the enlargement / reduction center position 32 at the time of adjustment. A pixel value is displayed on the interface screen 31 as the movement amount 34.

The central calculation unit 17a calculates adjustment information based on information such as the enlargement / reduction center position 32, the enlargement / reduction center movement direction 33, and the movement amount 34, and presents the calculation result on the adjustment information display screen 35. In the case of FIG. 6, the adjustment information display screen 35 is arranged on the right side of the interface screen 31. On the adjustment information display screen 35, the adjustment procedure 36, the simple light ray diagram 37, the adjustment target name 38, the pseudo knobs 39A and 39B, the knob rotation direction 40, and the adjustment amount 41 are displayed. Incidentally, the pseudo knob 39A is an adjustment knob for the X axis, and the pseudo knob 39B is an adjustment knob for the Y axis. The symbol "BT" representing the adjustment target name 38 represents the deflection coils 3 and 4.

Each time the set of images 19A and 19B displayed on the interface screen 31 is updated, the central calculation unit 17a executes the image processing program, and each time, the enlargement / reduction center position 32 and the enlargement / reduction center movement direction 33 are executed. , The movement amount 34 and the display contents of the adjustment information display screen 35 are updated. The operator refers to the information presented on the interface screen 31 and the adjustment information display screen 35, and adjusts the voltage axis center. As described above, in this embodiment, the adjustment work can be performed based on specific numerical values and objective information, and the adjustment variation and adjustment time difference between operators can be reduced.

This process is often similar to the process operation described in the first embodiment. Therefore, the basic processing operation is the same as that in FIG. In the case of this embodiment, the difference is that the calculation process of the rotation amount of S104 is unnecessary, the point of calculating the enlargement / reduction center position instead of the rotation center in S106, and the image from the enlargement / reduction center instead of the rotation center in S107. It is a point to calculate the moving distance to the center of. This is because the observed image at the time of adjusting the voltage axis does not rotate even if the voltage changes.

(2-3) Effects of Examples As described above, the TEM (Fig. 1) in this example provides various information that supports the changes that occur before and after the adjustment and the adjustment work during the electromagnetic axis adjustment work by the operator. It is calculated and displayed on the interface screen 31 and the adjustment information display screen 35. Therefore, the operator can perform the axis adjustment work with reference to an appropriate adjustment procedure and adjustment amount, and can reduce both the adjustment accuracy and the variation in the adjustment time difference.

(3) Example 3
(3-1) Device Configuration In this embodiment as well, the TEM having the configuration shown in FIG. 1 is used. In this embodiment, the operation when the operator adjusts the beam deflection fulcrum of the TEM will be described.

(3-2) Beam deflection fulcrum adjustment operation Even when adjusting the deflection fulcrum for tilting the electron beam of the TEM, the operator accesses the central calculation unit 17a through the operation of the operation panel and instructs the execution of the corresponding program. To do. The central calculation unit 17a controls the electron beam adjusting device 13 to change the current value of the irradiation system lens 2 and adjusts the electron beam so that it becomes a spot on the fluorescent plate 11. After that, the operator operates the operation panel to access the central arithmetic unit 17a and instructs the execution of the camera control program. The central calculation unit 17a that executes the camera control program captures the fluorescent screen 11 with the camera 9 and stores it in the image memory 17d (or 17e).

After that, the operator controls the electron beam adjusting device 13 through the operation of the operation panel, and changes the current value of both or one of the deflection coil 3 and the deflection coil 4. When the current value of the deflection coil 3 or the deflection coil 4 changes, the spot position of the electron beam irradiated to the fluorescent plate 11 changes. After that, the operator takes a picture of the fluorescent screen 11 with the camera 9 using the camera control program and stores it in the image memory 17e (or 17d). In this state, the central arithmetic unit 17a executes the image processing program stored in the program storage memory 17f and displays it on the display device 18.

FIG. 7 shows an example of the interface screen 51 and the adjustment information display screen 56 displayed when the beam deflection fulcrum is adjusted. On the interface screen 51, the reference spot 52A before the movement and the spot 53A after the movement are displayed. Further, the interface screen 51 displays the beam spot moving direction 54 and the moving amount 55 from the moved beam spot center position 53 toward the reference beam spot center position 52.

Further, on the adjustment information display screen 56, the adjustment procedure 57, the simple light ray diagram 58 at the time of adjustment, the adjustment target name 59, the pseudo knobs 60A and 60B, the knob adjustment direction 61, and the adjustment amount 62 are displayed. Incidentally, the pseudo knob 60A is an adjustment knob for the X axis, and the pseudo knob 60B is an adjustment knob for the Y axis. The symbol "BTX" representing the adjustment target name 59 represents the X-axis component of the deflection coils 3 and 4.

Each time the current value of the deflection coil 3 or the deflection coil 4 is changed, the central calculation unit 17a stores an image signal in the image memory 17d (or 17e). The image signal stored in the image memory 17d (or 17e) is required to obtain the reference beam spot center position 52. Therefore, this image signal is not discarded until the adjustment work of the beam deflection fulcrum is completed. A similar procedure can be applied to the adjustment of the deflection fulcrum for translating the electron beam.

FIG. 8 shows an example of a processing procedure of an image processing program executed by the central calculation unit 17a when adjusting the beam deflection fulcrum. The image processing program targets the image signal stored in the image memory 17d or 17e as a processing target, and executes calculation of information to be displayed on the interface screen 51 and the adjustment information display screen 56.

First, the central calculation unit 17a acquires a reference image signal from the image memory 17d (or 17e) (S301). A specific example of a reference image signal will be described with reference to FIG. FIG. 9 is an example of an observation image displayed on the interface screen 51 while adjusting the beam deflection fulcrum. The spot 52A shows the electron beam spot before changing the current value of the deflection coil 3 or 4, and the spot 53A shows the electron beam spot after changing the current value of the deflection coil 3 or 4. In S301, for example, an image signal in which only the spot 52A exists in the observation field of view is acquired.

Next, the central calculation unit 17a confirms whether or not the currents flowing through the deflection coil 3 and the deflection coil 4 have changed (S302). If there is no change, the central calculation unit 17a repeats the confirmation operation. When there is a change, the central arithmetic unit 17a acquires an image from the image memory 17e (or 17d) (S303). The image acquired at this time is, for example, an image in which only the spot 53A exists in the observation field of view.

When the two images are acquired, the central calculation unit 17a calculates the amount of movement of the beam spot based on the image in the image memory 17d (or 17e) and the image in the image memory 17e (or 17d) (S304). The formula for calculating the amount of movement ΔD is shown in Equation 8.

After that, the central calculation unit 17a calculates an adjustment value for adjusting the spot 53A to the position of the spot 52A based on the calculated movement amount ΔD (S305). In order to obtain the adjustment value, the central calculation unit 17a obtains the inclination angle of the electron beam with respect to the adjustment parameter as a calibration value. The calibration value is, for example, the movement vector (bx, by) of the beam spot per 1 mA of the current value of the deflection coils 3 and 4. Equation 9 shows an example of the calibration value.

Next, the central calculation unit 17a calculates the current value of the tilting coil for adjusting the spot 201 to the coordinates of the center of gravity of the spot 200 by using the parameters obtained at the time of calculating the adjustment value. The calculation formula is shown in Equation 10.

Finally, the central calculation unit 17a updates the interface screen 51 and the adjustment information display screen 56 by using the information of S304 and S305 (S306). The content of the update operation is the same as the procedure described with reference to FIG.

(3-3) Effects of Examples As described above, the TEM (Fig. 1) in this example provides various information that supports the changes that occur before and after the adjustment and the adjustment work during the electromagnetic axis adjustment work by the operator. It is calculated and displayed on the interface screen 51 and the adjustment information display screen 56. Therefore, the operator can perform the axis adjustment work with reference to an appropriate adjustment procedure and adjustment amount, and can reduce both the adjustment accuracy and the variation in the adjustment time difference.

(4) Example 4
(4-1) Device Configuration In this embodiment as well, the TEM having the configuration shown in FIG. 1 is used. In this embodiment, the operation when the operator adjusts the focus of the TEM will be described.

(4-2) Focus adjustment operation Even when the focus is adjusted, the operator instructs the execution of the program corresponding to the central calculation unit 17a through the operation of the operation panel or the like. The central arithmetic unit 17a that executes the program stores the fluorescent screen image taken by the camera 9 in the image memory 17d (or 17e). Further, the operator controls the electron beam adjusting device 13 through an operation panel or the like to change the current value of the deflection coil 3 or the deflection coil 4.

After the current value of the deflection coil 3 or the deflection coil 4 changes, the central calculation unit 17a stores the fluorescent screen image taken by the camera 9 in the image memory 17e (or 17d). After that, the central calculation unit 17a calculates the focus amount of the image from the image signals stored in the image memories 17d and 17e. The central calculation unit 17a displays the calculation result on the display device (interface unit) 18.

FIG. 10 shows an example of the interface screen 71 and the adjustment information display screen 76 displayed at the time of focus adjustment. On the interface screen 71, a dotted circle 72 indicating the target focus amount, a one-dot chain line circle 73 indicating the current focus amount, an arrow 74 indicating the direction of underfocus or overfocus, and the current focus amount 75 are displayed. Is displayed. On the other hand, the adjustment information display screen 76 displays the adjustment procedure 77, the simple light beam diagram 78 at the time of adjustment, the adjustment target name 79, the pseudo knob 80, the adjustment knob rotation direction 81, and the adjustment amount 82. The symbol "OBJ" representing the adjustment target name 79 represents the objective lens 5.

In the case of this embodiment, the central calculation unit 17a has the display content of the interface screen 71 (a dotted circle 72 representing the target focus amount, a alternate long and short dash line representing the current focus amount) each time the current value of the objective lens 5 changes. 73, an arrow 74 indicating the direction of underfocus or overfocus, the current focus amount 75), and the contents of the adjustment information display screen 76 are updated. Further, when the current value of the deflection coil 3 or the deflection coil 4 changes, the central calculation unit 17a alternately updates the image signals stored in the image memories 17d and 17e.

FIG. 11 shows an example of a processing procedure of an image processing program executed by the central calculation unit 17a at the time of focus adjustment. First, the central calculation unit 17a acquires the current value of the objective lens 5 (S401). Next, the central calculation unit 17a photographs one of the fluorescent screen image and the sample transmission image using the camera 9 or 10, stores the image signal in the image memory 17d (or 17e), and stores the image signal in the image memory 17d (or 17e). Alternatively, the image signal is acquired from 17e) (S402).

Subsequently, the central calculation unit 17a confirms whether or not the current value of the objective lens 5 has changed (S403). If there is no change, the central calculation unit 17a repeats the confirmation operation. When there is a change, the central arithmetic unit 17a acquires an image from the image memory 17e (or 17d) (S404).

After that, the central calculation unit 17a acquires an image signal from the image memories 17d and 17e, and calculates a required focus amount from the two images (S405). Specifically, the correlation value between the two images is taken for the calculation of the focus amount, and the movement amount between the two images is calculated. For the calculation of the movement amount, for example, there is a method using template matching. As the amount of movement, the amount of movement in two directions, the X direction and the Y direction, is required. If the sign of the amount of movement in the X direction at this time is "+", it is underfocus. When the sign is "-", it is overfocus.

Equation 11 shows an example of calculating the focus amount of the image. The variables used in Equation 11 will be described.

Here, Mag is the magnification of the device at the time of focus adjustment, and MagCam is the magnification of the camera. Further, Cs is a spherical aberration coefficient, and Focus is a focus amount calculated from the movement amount. Further, X is the amount of movement in the X direction between the two images, and Y is the amount of movement in the Y direction between the two images. BeamTilt is the tilt angle of the electron beam. By the way, the value of Cs needs to be obtained by experiments and simulations in advance. Other variables can be obtained from software that manages the device status.

The unit of the obtained Focus amount is "mm". The adjustment value set in the objective lens 5 can be calculated from the obtained Focus amount and the current value of the objective lens at the time of focus adjustment. As a method of obtaining the current value from the focus amount, for example, the relationship between the change in the current value of the objective lens 5 and the movement amount of the image is obtained in advance by an experiment, and the value is used to obtain the objective lens 5 required for the change in the focus amount. It is possible to obtain the current value of.

According to the calculation result, the central calculation unit 17a changes the display contents of the interface screen 71 and the adjustment information display screen 76 (S406). Specifically, on the interface screen 71, the central calculation unit 17a has a dotted circle 72 representing the target focus value, a one-dot chain line circle 73 representing the current focus amount, and an arrow indicating the direction of underfocus or overfocus. 74, the current focus amount 75 is displayed. Further, the central calculation unit 17a displays the adjustment procedure 77, the simple light ray diagram 78 at the time of adjustment, the adjustment target name 79, the pseudo knob 80, the adjustment knob rotation direction 81, and the adjustment amount 82 on the adjustment information display screen 76.

(4-3) Effect of Example As described above, the TEM (Fig. 1) in this example provides various information that supports the change and adjustment work that occurred before and after the adjustment during the electromagnetic axis adjustment work by the operator. It is calculated and displayed on the interface screen 71 and the adjustment information display screen 76. Therefore, the operator can perform the axis adjustment work with reference to an appropriate adjustment procedure and adjustment amount, and can reduce both the adjustment accuracy and the variation in the adjustment time difference.

(5) Functions Provided in Each Example As described above, the TEM having the image processing function according to the first to fourth embodiments includes current axis center adjustment, voltage axis center adjustment, beam deflection fulcrum adjustment, or focus adjustment. At the time of any adjustment, the following functions are executed.
(A) A function of displaying the position of the center of gravity (including the center position) of a figure characteristic on the observation screen on the display device 18 (b) A function of displaying the direction and amount of movement for axis adjustment (c) Adjustment procedure, simple ray diagram at the time of adjustment, adjustment target name, pseudo knob imitating a deflection coil or magnetic field lens operated at the time of adjustment, adjustment direction of the knob, adjustment amount (movement amount in pixel value units in the vertical direction, horizontal direction Function to display (including the amount of movement in pixel value units.) (D) Function to display the center of gravity of the image when it is rotated before and after the adjustment.

(6) Other Examples The present invention is not limited to the above-mentioned examples, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and does not necessarily have all the configurations described. In addition, a part of one embodiment can be replaced with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of another embodiment with respect to a part of the configuration of each embodiment. In each of the above-described examples, TEM is illustrated as an example of a charged particle beam apparatus, but in the present invention, signal electrons output from a surface region of a sample 6 irradiated with charged particles (for example, an electron beam). It can also be applied to axis adjustment of a scanning electron microscope (so-called SEM) for detecting (for example, secondary electrons, reflected electrons, etc.).

Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware, for example, by designing a part or all of them with an integrated circuit. Further, each of the above configurations, functions, and the like may be realized by the processor interpreting and executing a program that realizes each function (that is, in terms of software). Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, a hard disk, or SSD (Solid State Drive), or a storage medium such as an IC card, SD card, or DVD. In addition, the control lines and information lines indicate what is considered necessary for explanation, and do not represent all the control lines and information lines necessary for the product. In reality, it can be considered that almost all configurations are interconnected.

1 ... Electron gun 2 ... Irradiation system lens 3 ... 1st deflection coil 4 ... 2nd deflection coil 5 ... Objective lens 6 ... Sample 7 ... Sample stand 8 ... Imaging system lens 9 ... Camera (for fluorescent plate photography)
10 ... Camera (for transmission image shooting)
11 ... Fluorescent plate 12 ... Electron beam generator 13 ... Electron beam adjusting device 14 ... Sample moving device 15 ... Fluorescent plate drive device 16 ... Vacuum exhaust pump 17 ... Computer 17a ... Central arithmetic unit 17b ... Image display memory 17c ... Input / output interface 17d … Image memory 17e… Image memory 17f… Program storage memory 17g… Data storage memory

Claims (15)

An imaging device that captures an image of a sample generated by irradiation with a charged particle beam,
A deflection coil that deflects the charged particle beam and
A magnetic field lens that focuses the charged particle beam and
A control device that controls the deflection coil and the magnetic field lens,
It has an interface unit that displays information used for electromagnetic axis adjustment of the charged particle beam.
The control device is
As the information used for the electromagnetic axis adjustment,
A first that includes conversion characteristics inherent in the change between the two images, based on the two images acquired using the same imaging device before and after the manual electromagnetic axis adjustment by the operator . Calculate the information of
Based on the first information, it calculates a second information including one or both adjustment amount of the adjustment amount and the magnetic lens of said deflection coil to be adjusted to the operator,
A charged particle beam device that displays the first information and the second information on the interface unit. In the charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, characterized in that the information used for the electromagnetic axis adjustment is at least one of the information used for the current axis center adjustment, the voltage axis center adjustment, the beam deflection fulcrum adjustment, and the focus adjustment. In the charged particle beam apparatus according to claim 1,
The photographing device passed through the photographing device for photographing the surface image of the sample irradiated by the charged particle beam, the photographing device for photographing the image formed by the charged particle beam transmitted through the sample on the fluorescent screen, and the sample. A charged particle beam device, characterized in that it is any one or a combination of the photographing devices that directly capture an image of the charged particle beam. In the charged particle beam apparatus according to claim 1,
The first information is the amount of rotation between two images acquired using the same imaging device before and after the manual electromagnetic axis adjustment by the operator. Wire device. In the charged particle beam apparatus according to claim 1,
The first information is the vertical direction and the horizontal direction of a characteristic figure common between two images acquired by using the same photographing device before and after the manual electromagnetic axis adjustment by the operator. A charged particle beam device characterized by being a pixel value of the amount of movement in a direction. In the charged particle beam apparatus according to claim 5,
A charged particle beam device, characterized in that the pixel value is the length of a characteristic graphic on the screen. In the charged particle beam apparatus according to claim 1,
The first information is the center position or the center of gravity of a characteristic figure common between two images acquired by using the same photographing device before and after the manual electromagnetic axis adjustment by the operator. A charged particle beam device characterized by being a symbol indicating a position. In the charged particle beam apparatus according to claim 1,
The first information is a graphic that displays the amount of focus between two images acquired by using the same photographing device before and after the manual electromagnetic axis adjustment by the operator. Charged particle beam device. In the charged particle beam apparatus according to claim 1,
The second information is a charged particle beam apparatus including an adjustment procedure. In the charged particle beam apparatus according to claim 1,
The second information is a diagram in which the positional relationship between the deflection coil and the magnetic field lens is represented by a symbol or a diagram, and the trajectory of the charged particle beam passing through both or one of the magnetic field lens and the deflection coil is represented. A charged particle beam device characterized by including. In the charged particle beam apparatus according to claim 1,
The second information includes a name of both or one of the deflection coil and the magnetic field lens which is changed at the time of adjustment by the operator. In the charged particle beam apparatus according to claim 1,
The second information is a charged particle beam apparatus including a schematic diagram of a knob for the operator to adjust both or one of the adjustment amount of the deflection coil and the adjustment amount of the magnetic field lens. In the charged particle beam apparatus according to claim 12,
The second information is a charged particle beam apparatus including the rotation direction of the knob. In the charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the adjustment amount is a current value or a value corresponding to the current value corresponding to both or one of the deflection coil and the magnetic field lens which is changed at the time of adjustment by the operator. In addition to the charged particle beam apparatus according to claim 1,
The interface unit is a charged particle beam device that updates information used for the electromagnetic axis adjustment in real time.

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