JP2018113171A - Method for adjusting focus of charged particle beam apparatus, and charged particle beam apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for adjusting the focus of a charged particle beam apparatus and a charged particle beam apparatus which are arranged so that focus evaluation values are calculated from image data sequentially obtained according to an operation on input means, and the change in focus evaluation value showing the focusing state of an obtained image can be displayed in real time and as such, a user concerned can more readily adjust the focus manually in a short time by visually checking the change in the focusing state of an image.SOLUTION: A charged particle beam apparatus applies a charged particle beam to an observation region of a sample, obtains image data of the observation region, displays an image on display means, and controls focus adjustment means based on a focus adjustment amount input from input means to perform the focus adjustment of the image. A method for adjusting the focus of the charged particle beam apparatus comprises the steps of: performing a focus-evaluating calculation based on image data sequentially obtained according to an operation on the input means to sequentially obtain focus evaluation values; and displaying the time-series change in the focusing state of an image based on the focus evaluation values thus obtained.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a focus adjustment method for a charged particle beam device and a charged particle beam device.

  FIG. 10 shows a configuration of a general transmission electron microscope which is one of charged particle beam apparatuses. The electron beam EB emitted from the electron beam source 2 in the transmission electron microscope column 1 in FIG. 10 is irradiated on the sample 4 through the objective lens 5 with the amount of current adjusted by the irradiation system lens group 3. . The transmission electron beam transmitted through the sample 4 arranged in the magnetic field formed by the objective lens 5 is enlarged and formed by the objective lens 5 and the imaging system lens group 6 and projected onto the fluorescent plate 7. The image projected on the fluorescent screen 7 is converted into a video signal by the CCD camera 8 and sent to the image forming processing unit 10 in the control device 9. This video signal is converted into digital image data by removing noise by the image forming processing unit 10, and then displayed on the screen of the display device 11 as a transmission electron image having sample information. The irradiation system lens group 3, the objective lens 5, and the imaging system lens group 6 described above are controlled by the electron microscope main body control unit 12 in the control device 9.

  An observation image display screen 14 and an operation screen 15 as shown in FIG. 11 are displayed on the screen of the display device 11 described above, and a transmission electron image (hereinafter referred to as “observation image”) is displayed on the observation image display screen 14. The operation screen 15 displays buttons or the like to be controlled (not shown), and selects the object to be controlled by the input device 13 connected to the control device 9 in FIG. Be able to. The input device 13 is, for example, an operation panel, a mouse, a keyboard or the like provided with buttons and a knob.

  In the transmission electron microscope having such a configuration, the focus adjustment for projecting a clear transmitted electron image on the fluorescent screen 7 is performed by a current supplied to the objective lens 5 by the electron microscope main body control unit 12 in the control device 9. By adjusting the amount (excitation current amount), the focal position of the transmitted electrons transmitted through the sample 4 is adjusted.

  When manually adjusting the focus, the input device 13 presses the focus button 16 installed on the operation panel 13 ′ shown in FIG. 12, for example, and then dial-type objective lens variable current knob 17 (hereinafter referred to as “knob 17”). The input value is changed by turning (turning) clockwise or counterclockwise, and the amount of current (directly supplied to the objective lens 5 via the electron microscope main body control unit 12 in the control device 9) is changed. (Excitation current) can be continuously changed, so that the focal position of the objective lens 5 is adjusted, and the observation image displayed on the observation image display screen 14 of the display device 11 is set to the optimum focus (just focus). Can be matched.

  When the focus is automatically adjusted, the focus position of the objective lens 5 is automatically adjusted by activating an automatic focus adjustment function (not shown) incorporated in the electron microscope main body control unit 12 for observation. The image can be adjusted to the optimum focus (just focus). A sample of a transmission electron microscope is observed using such a focus adjustment method.

  Hereinafter, an operation procedure of focus adjustment at the time of sample observation of the transmission electron microscope will be described with reference to FIGS. FIG. 13 is a flowchart showing a conventional focus adjustment procedure.

  In step S1 in FIG. 13, the user first determines whether or not to perform automatic focus adjustment. When performing automatic focus adjustment (step S1: Yes), the process proceeds to step S2, and the user presses the automatic focus adjustment button 18 on the operation panel 13 ′ shown in FIG. 12, for example. Then, the control device 9 activates an automatic focus adjustment function (not shown) in the electron microscope main body control unit 12 to execute the automatic focus adjustment, and after the automatic focus adjustment is performed on the observation image display screen 14 of the display device 11. Display the observation image.

  Next, in step S3, the user confirms the observation image (TEM image) displayed on the observation image display screen 14 of the display device 11, and visually determines whether or not the observation image has an optimum focus (just focus). To do. When the observation image has the optimum focus (just focus) (step S3: Yes), the focus adjustment is completed, but when the observation image is not the optimum focus (step S3: No), the process proceeds to step S4.

  In step S4, the user confirms the degree of blurring of the observation image on the observation image display screen 14 of the display device 11, presses the focus button 16 on the operation panel 13 ′ of the input means shown in FIG. Turn the dial clockwise or counterclockwise to adjust the focus amount of the observation image.

  Next, after manual focus adjustment, when it is visually determined in step S3 that the observation image has the optimum focus (just focus) (step S3: Yes), the focus adjustment ends.

  Note that the above-described automatic focus adjustment technique is disclosed in, for example, Patent Document 1.

Japanese Patent No. 5373463

  Now, when performing focus adjustment with a transmission electron microscope, the user's experience, such as the degree of understanding of the operation method of the operation panel and the optimal focus adjustment method, greatly affects the results. Visual judgment by the user is required. In particular, it is difficult to find the optimum focus point. For example, when adjusting the focus of a TEM image, it depends largely on the experience and proficiency of the observer.

  In addition, as described above, whether or not the focus adjustment is good is a visual judgment of the image. Therefore, there is an automatic focus adjustment function to suppress variations due to the visual judgment, but this automatic focus adjustment function is effective for any image. It is not equipped with a versatile algorithm that works well, and the calculation time is long. Therefore, if automatic focus adjustment is used many times, it has contributed to lowering usability. For example, in the case of a sample that is easily damaged by an electron beam, if automatic focus adjustment is executed many times, the time required for the automatic focus adjustment becomes longer, and there is a problem that the sample damage increases accordingly.

  The present invention has been made in view of such a problem, and calculates a focus evaluation value from image data sequentially obtained in accordance with an operation of an input unit, and changes in the focus evaluation value of the obtained image in real time. It is an object of the present invention to provide a charged particle beam device focus adjustment method and a charged particle beam device for display.

  In order to solve the above-described problems, a charged particle beam apparatus for adjusting a focus of a charged particle beam apparatus according to the present invention irradiates an observation region of a sample with a charged particle beam, acquires image data of the observation region, and displays an image on a display unit. In a focus adjustment method for a charged particle beam apparatus, wherein the focus adjustment unit controls the focus adjustment unit based on a focus adjustment amount input from the input unit to adjust the focus of the image. The focus evaluation calculation is performed based on the obtained image data, the focus evaluation values are sequentially acquired, and the time-series changes in the focus state of the image are displayed based on the acquired series of focus evaluation values. Yes.

  The charged particle beam apparatus according to the present invention irradiates the observation region of the sample with the charged particle beam, acquires image data of the observation region, displays the image on the display unit, and adjusts the focus adjustment amount input from the input unit. A charged particle beam device that performs focus adjustment of the image by controlling a focus adjustment unit based on the focus, and performing a focus evaluation calculation based on image data obtained in accordance with an operation of the input unit to calculate a focus evaluation value An evaluation value calculation unit; and a focus evaluation value display unit that displays a series of focus evaluation values calculated by the focus evaluation value calculation unit in accordance with the operation of the input unit and displays a time-series change in the focus state of the image. It is characterized by that.

  According to the focus adjustment method of the charged particle beam apparatus of the present invention, it is possible to display a numerical change in the focus evaluation value representing the focus state from the acquired observation image by automatically detecting the focus adjustment operation. Even in the case of a TEM image in which it is difficult to find an optimum focus point, for example, the user can visually confirm that the current focus adjustment is appropriately performed by looking at the change in the focus evaluation value.

  In addition, according to one aspect of the present invention, since the change in the focus evaluation value of the image is automatically displayed in real time when it is necessary without disturbing the user's work, manual focus adjustment work by the user Can be improved.

  In addition, according to one embodiment of the present invention, the focus adjustment can be performed in a short time even in a sample in which the autofocus function does not work effectively and is easily affected by an electron beam.

It is a figure which shows an example of a structure of the transmission electron microscope which concerns on embodiment of this invention. It is a figure which shows an example of a structure of the manual focus adjustment auxiliary control part which concerns on the form of this invention. It is a flowchart for demonstrating the operation procedure of embodiment of this invention. It is a screen displayed on the screen of the display apparatus for demonstrating the Example of this invention. It is a figure which shows the graph I for manual focus adjustment of this invention. It is a figure explaining the graph I for manual focus adjustment of this invention. It is a figure which shows the graph II for manual focus adjustment of this invention. It is a figure explaining the graph II for manual focus adjustment of this invention. It is a figure explaining the graph II for manual focus adjustment of this invention. It is a figure which shows an example of a structure of the transmission electron microscope which concerns on the conventional embodiment. It is a figure explaining an example of the screen of the conventional display apparatus. It is a figure explaining an example of the operation panel which concerns on the conventional input device. It is a flowchart for demonstrating the operation procedure of the conventional focus adjustment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of the configuration of a transmission electron microscope according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those used in FIG. 10 denote the same components.

  In FIG. 1, 19 is a manual focus adjustment auxiliary control unit that is provided in the control device 9 and controls a function for assisting manual focus adjustment, and monitors the focus adjustment operation of the input device 13 as shown in FIG. An input operation monitoring unit 20, a focus evaluation value calculation unit 21 that calculates a numerical value (focus evaluation value) representing a focus state from the acquired observation image, and a focus evaluation value display unit 22 that displays a change in the focus evaluation value of the observation image It is composed of

  The input operation monitoring unit 20 includes an operation detection unit 20a and an operation stop detection unit 20b. The operation detection unit 20a is set with a preset operation time t1, which is a preset threshold value. When the user performs a focus adjustment operation, the operation time of the input device 13 is measured and measured. When the set time exceeds the set operation time t1, a detection signal is output. The operation stop detection unit 20b is set with a preset operation stop time t2, which is a preset threshold.When the user stops the focus adjustment operation, the operation stop time of the input device 13 is measured, When this operation stop time exceeds the set operation stop time t2, a stop signal is output.

  The focus evaluation value calculation unit 21 described above includes a calculation image acquisition unit 21a and a calculation processing unit 21b. The calculation image acquisition unit 21a acquires data of an observation image being observed from the image formation processing unit 10 that forms a video signal obtained by photographing the microscope image projected on the fluorescent screen 7 with the CCD camera 8 into image data. Is. The arithmetic processing unit 21b performs arithmetic processing on the image data of the observation image sent from the arithmetic image acquisition unit 21a to obtain a focus evaluation value, and quantifies and outputs the result.

  The focus evaluation value display unit 22 described above graphs the numerical value output from the focus evaluation value calculation unit 21 and outputs the graph to the display device 11.

  With reference to FIGS. 1 to 4 and 12, the operation procedure of focus adjustment (focusing) to which the manual focus adjustment assist function of the present invention is applied in the transmission electron microscope configured as described above will be described. FIG. 3 is a flowchart illustrating an example of the focus adjustment operation procedure according to the embodiment of the present invention.

  First, when the control device 9 is activated, the electron microscope main body control unit 12, the image formation processing unit 10, and the manual focus adjustment auxiliary control unit 19 are also activated. When the manual focus adjustment auxiliary control unit 19 starts up, the operation detection unit 20a of the input operation monitoring unit 20 and the operation stop detection unit 20b in the manual focus adjustment auxiliary control unit 19 operate the knob 17 on the operation panel 13 '(user Monitoring of the focus state of the sample image by (operation to adjust) is started.

  In step S20 in FIG. 3, the user determines whether or not to perform automatic focus adjustment. When executing the automatic focus adjustment (step S20: Yes), the process proceeds to step 30, and the user presses the automatic focus adjustment button 18 on the operation panel 13 ′ of FIG. Then, the control device 9 activates an automatic focus adjustment function (not shown) in the electron microscope main body control unit 12 to execute the automatic focus adjustment, and displays the observation image after the automatic focus adjustment on the screen of the display device 11. Let

  Next, in step S40, the user looks at the observation image displayed on the observation image display screen 14 of the display device 11, and visually determines whether or not this observation image has an optimum focus. When the observation image is in the optimum focus (just focus) (step S40: Yes), the focus adjustment is completed, but when the observation image is not the optimum focus (step S40: No), the process returns to step S20 again to automatically adjust the focus. (Step S20: No), the process proceeds to Step S50 and Step S60.

  First, in step S50, the user presses the focus button 16 on the operation panel 13 ′ and turns the knob 17 to execute the adjustment for focusing the observation image displayed on the observation image display screen 14 of the display device 11. . Then, in step S60, the operation detection unit 20a of the input operation monitoring unit 20 constantly monitors the operation of the knob 17 on the operation panel 13 ′ (when the focus is adjusted, the rotation state of the knob 17 by the user). The time during which the knob 17 on the operation panel 13 ′ is operated is measured, and this measured operation time is compared with a preset operation time t1 that is a preset threshold value. This operation time is within the set operation time t1. When the operation time is opposite, when the measured operation time exceeds the set operation time t1, the detection signal is immediately output to the focus evaluation value calculation unit 21 and the focus evaluation value display unit 22 and the measurement time is set. Reset to zero.

  Next, in step S70, when the detection signal output from the input operation monitoring unit 20 described above is input to the focus evaluation value calculation unit 21, the calculation image acquisition unit 21a in the focus evaluation value calculation unit 21 is the image formation processing unit. 10, the image data of the observation image under observation, which is focus-adjusted based on the focus adjustment amount input in accordance with the operation of the knob 17 on the operation panel 13 ′, is acquired and immediately sent to the arithmetic processing unit 21b. Thereafter, the calculation image acquisition unit 21a sequentially receives the image data of the latest observation image being observed from the image formation processing unit 10 at regular time intervals (ΔT) until a stop signal (described later) is received. The process of acquiring and immediately sending to the arithmetic processing unit 21b is repeated.

  Next, in step S80, the arithmetic processing unit 21b of the focus evaluation value calculating unit 21 immediately performs arithmetic processing on the image data of the observation images sequentially obtained from the arithmetic image acquiring unit 21a, and the numerical value resulting from the arithmetic processing is subjected to focus evaluation. The value is output to the focus evaluation value display unit 22 as a value. The focus evaluation value display unit 22 plots a series of focus evaluation values sequentially obtained from the focus evaluation value calculation unit 21 on the manual focus adjustment auxiliary screen 23 on the screen of the display device 11 in real time, and displays the focus state of the image. Display time-series changes in a graph.

Note that, in the arithmetic processing unit 21b of the focus evaluation value calculating unit 21 described above, for example, one digitized observation image sent from the calculation image acquisition unit 21a is used as one pixel image of one observation image close to each other. After multiplying the intensity values of the pixel signals in the direction, all the multiplied values are added and calculated as one numerical value, and the calculated numerical value is output as a focus evaluation value.
Since the focus evaluation value representing the focus state obtained from the obtained observation image is plotted in real time on the manual focus adjustment auxiliary screen 23 described above, the user can observe the graph on the manual focus adjustment auxiliary screen 23 while viewing the graph. The amount of current supplied to the objective lens 5 is adjusted by turning the knob 17 on the operation panel 13 ′ to change the input value, and the observation image on the observation image display screen 14 is adjusted to the optimum focus (just focus). is there.

  By the way, in the operation stop detection unit 20b in the input operation monitoring unit 20 in step S90, the operation stop time during which the operation of the knob 17 on the operation panel 13 ′ is stopped (the time when the user does not operate (the knob 17 does not rotate). When the operation stop time is within the set operation stop time t2 by comparing the measured operation stop time with the threshold setting operation stop time t2 that is a preset threshold ( In step S90: No), the process returns to step S70 again, executes step S70, and then executes step S80. The focus evaluation values calculated in this step are plotted on the manual focus adjustment auxiliary screen 23.

On the other hand, when the operation stop time exceeds the set operation stop time t2 (step S90: Yes), the operation stop detection unit 20b of the input operation monitoring unit 20 sends a stop signal to the focus evaluation value calculation unit 21 and the focus evaluation value display unit 22. The process proceeds to step S100, and the calculation image acquisition unit 21a of the focus evaluation value calculation unit 21 that has received the stop signal stops acquiring image data of the observation image from the image formation processing unit 10, and receives the stop signal. The evaluation value display unit 22 ends the display of the manual focus adjustment auxiliary screen 23 from the screen of the display device 11 shown in FIG. That is, when the user moves away from the focus adjustment (focusing) operation by the operation panel 13 ′ for a certain time or more, the input operation monitoring unit 20 determines that the operation by the knob 17 on the operation panel 13 ′ is finished, and this determination Since the focus evaluation value display unit 22 erases the manual focus adjustment auxiliary screen 23 from the screen of the display device 11 based on this, the display of the manual focus adjustment auxiliary screen 23 does not interfere with other adjustment operations. .
Subsequently, when the focus adjustment operation is completed in step S50, the process proceeds to step S101, and the user visually determines whether or not the observation image has the optimum focus while viewing the observation image display screen 14 of the display device 11. If the observation image is not in the optimum focus state (step S101: No), the process returns to step S50 and step S60 again, and the user moves the knob 17 on the operation panel 13 ′ while looking at the graph on the manual focus adjustment auxiliary screen 23. Rotate to change the input value to adjust the amount of current supplied to the objective lens 5, align the observation image on the observation image display screen 14 with the optimum focus (just focus), and optimize the observation image (just focus) ) (Step S101: Yes), the focus adjustment ends.

  Next, a graph for manual focus adjustment displayed on the above-described manual focus adjustment auxiliary screen 23 will be described.

  First, a graph that displays the focus state of an image as a time-series change will be described. In order to generate this graph, in the manual focus adjustment auxiliary control unit 19 in the control device 9, the calculation image acquisition unit 21b in the focus evaluation value calculation unit 21 is transmitted from the operation detection unit 20a in the input operation monitoring unit 20. When the detection signal is received, the image data of the latest observation image being observed taken by the CCD camera 8 from the image formation processing unit 10 is sequentially acquired at regular time intervals (ΔT) and immediately sent to the arithmetic processing unit 21b. The arithmetic processing unit 21b performs arithmetic processing on the image data of the observation image sent from the arithmetic image acquisition unit 21a, calculates a focus evaluation value as a result of the arithmetic processing, sends the focus evaluation value to the focus evaluation value display unit 22, and performs focus evaluation. The value display unit 22 plots sequentially obtained focus evaluation values on the manual focus adjustment auxiliary screen 23 of the display device 11 at a constant time interval (ΔT) in time series, and graphs the change in the focus state of the image. Process .

  By executing such processing, a biaxial display graph I including a time axis and a focus evaluation value as shown in FIG. 5 is displayed on the manual focus adjustment auxiliary screen 23 of the display device 11, for example. In graph II in the figure, the latest focus evaluation value is always plotted at the left end, and when the latest focus evaluation value is plotted at a certain time interval (ΔT), the already plotted focus evaluation value is the right arrow. The scroll display moves in the direction of.

  In the region R1 in FIG. 5, the knob 17 on the operation panel 13 ′ is turned in one direction, and subsequently, in the region R2, the focus evaluation value when the knob 17 on the operation panel 13 ′ is returned in the opposite direction. It shows a change. If the focus evaluation value indicates the maximum value as shown in the figure, the maximum value is the optimum focus (just focus). While viewing the graph I on the manual focus adjustment auxiliary screen 23, the user adjusts by turning the knob 17 on the operation panel 13 'so that the latest focus evaluation value becomes the maximum value. For example, FIG. 6 shows a graph on the manual focus adjustment auxiliary screen 23 when the focus is adjusted to the optimum focus (just focus).

  An example in which the focus evaluation value is displayed by another display method will be described. In order to generate this graph, in the manual focus adjustment auxiliary control unit 19 in the control device 9, the calculation image acquisition unit 21a in the focus evaluation value calculation unit 21 is changed from the operation detection unit 20a in the input operation monitoring unit 20. When the detection signal is received, image data of the latest observation image being observed taken by the CCD camera 8 from the image formation processing unit 10 is sequentially acquired at regular time intervals (ΔT), and at the same time, the electron microscope main body control unit 12 The focus adjustment amount input from the input device 13 is also acquired sequentially, and the obtained image data of the observation image and the focus adjustment amount are linked, and then immediately sent to the arithmetic processing unit 21b. The arithmetic processing unit 21b is sent to The image data of the observation image associated with the amount of focus adjustment that came is calculated and processed to calculate the focus evaluation value and send it to the focus evaluation value display unit 22. The focus evaluation value display unit 22 sequentially obtains the acquired focus evaluation value. display Plotted for each focus adjustment amount on the manual focus adjustment support screen 23 of location 11, performs processing to graph the change in the focus state of the image.

  By executing such processing, the graph II of the biaxial display composed of the focus adjustment amount axis and the focus evaluation value as shown in FIG. 7 is displayed on the manual focus adjustment auxiliary screen 23 of the display device 11, for example. The In the graph II in the figure, the latest focus evaluation values are plotted with, for example, a cross-shaped figure that is visually emphasized, and the other focus evaluation values are plotted with, for example, black dots. Note that the focus evaluation values in FIG. 7 vary, but this is due to the influence of the magnetic hysteresis of the objective lens 5.

  In the case of this graph II, for example, the following functions are provided in order to set the observation image to an optimum focus (just focus).

  First, as an example, there is a case where a scroll bar 24 having a focus adjustment amount interlocked with the rotation of the knob 17 on the operation panel 13 ′ is provided on the manual focus adjustment auxiliary screen 23. In this case, the focus evaluation value display unit 22 has a function of moving the scroll bar 24 in accordance with the amount of rotation of the knob 17 on the operation panel 13 ′. When the user turns the knob 17 and adjusts the broken line extending vertically from the scroll bar 24 to the maximum focus evaluation value while viewing the manual focus adjustment auxiliary screen 23 shown in FIG. 8, the observation image on the observation image display screen 14 is displayed. Is the optimum focus (just focus).

  As another example, a setting button 25 for setting the maximum value of the focus evaluation value may be provided on the manual focus adjustment auxiliary screen 23. In this case, the manual focus adjustment auxiliary control unit 19 displays a setting button 25 on the manual focus adjustment auxiliary screen 23, and when this button 25 is clicked, the focus adjustment amount corresponding to the maximum value of the graph is displayed. A function for setting the objective lens 5 via the control unit 12 is provided. As shown in FIG. 9, even when the latest focus evaluation value is out of the maximum value, when the user clicks the setting button 25, the manual focus adjustment auxiliary control unit 19 takes the maximum focus evaluation value. Since the adjustment amount is calculated and this focus adjustment amount is set to the objective lens 5 via the electron microscope main body control unit 12, the observation image displayed on the observation image display screen 14 of the display device 11 is automatically optimized. Focus (just focus).

  As described above, according to the present invention, the focus evaluation value is calculated from the image data sequentially obtained in accordance with the operation of the input means, the change in the focus evaluation value of the obtained image is displayed in real time, and the focus state of the image Therefore, a clear observation image can be obtained even for a beginner who has little experience or proficiency of the user, such as an understanding degree of the operation method of the operation panel and an optimum focus adjustment method.

  In the graph II displaying the two axes including the focus adjustment amount axis and the focus evaluation value in the embodiment, the latest focus evaluation value and the focus adjustment amount at that time are always plotted on the left end, and already plotted. Alternatively, a scroll display may be used in which the focus evaluation value and the focus adjustment amount are moved in the right direction.

  In the above-described embodiment, an example in which the knob 17 (objective lens current amount variable knob) is installed on the operation panel 13 ′ as the input means has been described. However, the input means is displayed on the operation screen 15 of the display device 11, An input unit having a function of inputting an input value in order to vary the amount of current of the objective lens 5 may be used. In this case, the input operation monitoring unit 20 in the manual focus adjustment auxiliary control unit 19 operates an input unit having a function of changing the amount of current of the objective lens 5 on the operation screen 15 of the display device 11, for example, the number of numerical inputs, The number of clicks or the like is monitored, and the manual focus adjustment auxiliary screen 23 is displayed on the screen of the display device 11 by comparison with a preset threshold value.

  In addition, the input operation monitoring unit 20 constantly monitors the exchange of signals related to the focus adjustment operation at a connection unit (not shown) connected to the input device 13 provided in the control device 9, and the input device 13 The rotation time and stop time of the knob 17 are measured, and the manual focus adjustment auxiliary screen 23 is displayed on the screen of the display device 11 by comparing and comparing each measured measurement time with a preset threshold value. May be.

  In addition, the calculation processing in the calculation processing unit 21b of the focus evaluation value calculation unit 21 of the embodiment is not limited to the calculation processing shown in the present embodiment, and the image acquired in accordance with the operation of the input unit is not limited. Any method of arithmetic processing may be used as long as a numerical value representing the focus state can be obtained. For example, there is a calculation process for obtaining a numerical value for evaluating the focus state of the image from the differential value dispersion by differentiating the pixel signal intensity of the image.

  In the above-described embodiment, the transmission electron microscope has been described as an example. However, the manual focus of the present invention is included in a control device for a charged particle beam device such as a scanning transmission microscope, a scanning electron microscope, or a focused ion beam device. An adjustment auxiliary control unit 19 can also be provided. In this case, an image of the observation image formed by the image forming processing unit 10 based on the detection signal detected by the detector of electrons (secondary electrons, reflected electrons, X-rays) generated from the sample by irradiation of the charged particle beam. The manual focus adjustment auxiliary control unit 19 of the present invention is executed using the data.

DESCRIPTION OF SYMBOLS 1 ... Transmission electron microscope barrel, 2 ... Electron beam source, 3 ... Irradiation system lens group, 4 ... Sample, 5 ... Objective lens, 6 ... Imaging system lens group, 7 ... Fluorescent plate, 8 ... CCD camera, 9 ... Control device, 10 ... image formation processing unit, 11 ... display device, 12 ... electron microscope main body control unit, 13 ... input device, 13 '... operation panel, 14 ... observation image display screen, 15 ... operation screen, 16 ... focus button , 17... Objective lens current amount variable knob, 18... Automatic focus adjustment button, 19. Manual focus adjustment auxiliary control unit, 20... Input operation monitoring unit, 20 a ... operation detection unit, 20 b ... operation stop detection unit, 21. Value calculation unit, 21a ... calculation image acquisition unit, 21b ... calculation processing unit, 22 ... focus evaluation value display unit, 23 ... manual focus adjustment auxiliary screen, 24 ... scroll bar, 25 ... setting button

Claims (6)

A charged particle beam apparatus that irradiates an observation region of a sample with a charged particle beam, acquires image data of the observation region, and displays an image on a display unit. The focus adjustment unit includes a focus adjustment unit based on a focus adjustment amount input from the input unit. In a focus adjustment method of a charged particle beam device that performs control and focus adjustment of the image,
Focus evaluation calculation is performed on the basis of image data sequentially obtained in accordance with the operation of the input means to sequentially acquire focus evaluation values, and time-series changes in the focus state of the image are performed based on the series of acquired focus evaluation values. A method for adjusting a focus of a charged particle beam device, characterized in that display is performed. 2. The time-series change display of the focus state of the image is performed by two-axis display of a time axis and a focus evaluation value or two axes display of a focus adjustment amount axis and a focus evaluation value. The focus adjustment method of the described charged particle beam apparatus. 3. The display according to claim 1, wherein the end of the operation by the input unit is determined, and the display of the time-series change in the focus state of the image is ended when it is determined that the operation is ended. Focus adjustment method for charged particle beam apparatus. The charged particle beam is irradiated onto the observation area of the sample to acquire image data of the observation area and display the image on the display means, and the focus adjustment means is controlled based on the focus adjustment amount input from the input means to A charged particle beam device that performs focus adjustment,
A focus evaluation value calculation unit that calculates a focus evaluation value by performing a focus evaluation calculation based on image data obtained in accordance with the operation of the input unit;
A focus evaluation value display unit that displays a time-series change in the focus state of the image based on a series of focus evaluation values calculated by the focus evaluation value calculation unit in accordance with the operation of the input unit. A charged particle beam device. The focus evaluation value display unit displays time-series changes in the focus state of an image by biaxial display of a time axis and a focus evaluation value or biaxial display of a focus adjustment amount axis and a focus evaluation value. The charged particle beam apparatus according to claim 4. A determination unit that determines the end of the operation by the input unit is provided, and when the determination unit determines that the operation is ended, the display of the time-series change in the focus state of the image by the focus evaluation value display unit is ended. The charged particle beam apparatus according to claim 4 or 5, wherein the charged particle beam apparatus is configured as described above.

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