JP2004158392A - Electron microscope, method for operating electron microscope, operating program of electron microscope and computer readable recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate searching a field by registering an observed image by a suitable magnification on another screen. <P>SOLUTION: An electron microscope can display the observed image on a display unit 28 by applying an acceleration voltage to an electron gun to irradiate a sample with an electron beam based on predetermined image observation conditions, scanning the desired area of the surface of the sample while secondary electrons or reflected electrons emitted from the sample are detected by one or more detectors, thereby focusing the image. The display unit 28 includes a first display region 47 for displaying the image observing at present real time, and a second display region 48 provided on another screen from the region 47 to display the image displayed on the region 47 by registering at predetermined timing. The observation magnification of the image registered with the region 48 is set lower than that displayed on the region 47 at the registering time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electron microscope of a scanning type, a transmission type, and the like, an operation method thereof, an electron microscope operation program, and a computer-readable recording medium.
[0002]
[Prior art]
Today, as a magnifying observation apparatus for enlarging a minute object, an electron microscope using an electronic lens is used in addition to an optical microscope using an optical lens, a digital microscope, and the like. An electron microscope is a device in which an electron traveling direction is freely refracted and an imaging system such as an optical microscope is designed to be electron-optical. Electron microscopes include a transmission type that images electrons transmitted through a sample or specimen using an electron lens, a reflection type that images electrons reflected on the sample surface, and a convergent electron beam that scans the sample surface. There are a scanning electron microscope that forms an image using secondary electrons from each scanning point, and a surface emission type (field ion microscope) that forms electrons emitted from a sample by heating or ion irradiation.
[0003]
2. Description of the Related Art A scanning electron microscope (SEM) is a secondary electron detector and a reflected electron detector that detect secondary electrons and reflected electrons generated when a target sample is irradiated with a thin electron beam (electron probe). It is an apparatus that observes mainly the surface morphology of a sample by taking out using each detector and displaying it on a display screen such as a cathode ray tube or an LCD. On the other hand, a transmission electron microscope (TEM) is a technique in which an electron beam is transmitted through a thin film sample, and electrons scattered and diffracted by atoms in the sample are obtained as an electron diffraction pattern or a transmission electron microscope image. Mainly allows the internal structure of the substance to be observed.
[0004]
When an electron beam is applied to a solid sample, it penetrates through the solid due to the energy of the electrons. At that time, the interaction with the nuclei and electrons that make up the sample causes elastic collision, elastic scattering and energy loss. This produces elastic scattering. Inelastic scattering excites electrons in the shell of the sample element, excites X-rays and the like, emits secondary electrons, and loses energy corresponding to them. The amount of secondary electrons emitted differs depending on the angle of impact. On the other hand, reflected electrons scattered backward by elastic scattering and emitted again from the sample are emitted in an amount specific to the atomic number. The SEM utilizes these secondary electrons and reflected electrons. The SEM irradiates a sample with electrons, detects emitted secondary electrons and reflected electrons, and forms an observation image.
[0005]
When observing an image of a sample using the SEM, the image of a desired region of the sample is observed by mechanically moving or rotating the sample stage in the XY directions. In addition, the movement and rotation of the observation range are not limited to mechanical ones, but can also be performed by an image shift function that controls the deflection range of the electron beam or a scan rotation function that electrically rotates the two-dimensional scanning direction of the electron beam. It is.
[0006]
SEM enables observation from several times to several hundred thousand times. As described above, the SEM has a wide range of observable magnification, that is, a wide dynamic range, and has a high observable maximum magnification as compared with an optical microscope. Therefore, it is necessary to search for a visual field to obtain a desired image. In order to facilitate visual field searching, SEM observation is usually started at low magnification. First, after grasping the whole image of the sample at a low magnification, a part to be observed is designated, enlarged, and shifted to a high magnification. In the process of further expansion, movement adjustment of the observation position such as movement of the sample stage (stage) is also performed.
[0007]
In such a visual field search process, if a visual field search is performed with only one observation screen, a desired portion may be lost when the magnification becomes high. In such a case, it is necessary to temporarily reduce the magnification until it is possible to grasp which position on the sample the current observation field looks at. If the observation field of view can be grasped, the user can return to searching for the field of view again.
[0008]
As a technique to ensure that you do not lose sight of the part you want to observe when searching for a visual field, a still image obtained by observing the entire image of the sample at a low magnification, in addition to the main screen for observation, is stored on another screen (sub screen). There has been developed a method of displaying by providing (for example, Patent Document 1). According to this method, it is possible to confirm which position on the sub-screen having a low magnification and a wide field of view the observation screen being displayed on the main screen is located, so that it is easy to find the field of view.
[0009]
[Patent Document 1]
JP-A-2000-357481, FIG.
[0010]
[Problems to be solved by the invention]
However, the magnification of the still image registered on the navigation screen by this method is the observation magnification at the time of acquiring the still image. That is, at the time of registration of a still image, a sub-screen is acquired with the magnification being displayed on the observation main screen, and the magnification registered on the sub-screen cannot be changed from the magnification of the main screen. If the magnification of the image registered on the sub-screen is always fixed to the observation magnification displayed on the main screen, it may be inconvenient.
[0011]
For example, when the magnification of the observation image being displayed on the main screen is much higher than the magnification of the sub screen, it is very difficult to know which position of the sub screen the main screen is observing. In such a case, it is necessary to increase the magnification of the sub-screen and re-register. However, for the re-registration, once reduce the magnification of the main screen to a fraction of the current observation magnification, and then register the sub-screen. It is necessary to return to the original high magnification again, which is troublesome.
[0012]
Alternatively, in a case where the same sample is repeatedly observed, it is preferable to register the sub-screen at an optimum observation magnification according to the sample. However, in the above method, it is necessary to set the observation magnification of the main screen once to a magnification suitable for the sample, register the sub-screen, and then return to the original observation magnification, which is troublesome. In particular, an electron microscope such as an SEM has a slow time (frame rate) required to capture one observation image, and has a poor S / N ratio if only one observation image is used. Display processing is being performed. For this reason, changing the magnification of the observation image requires several seconds to several tens of seconds, and the response tends to be poor. Therefore, it is desirable to avoid time-consuming operations.
[0013]
The present invention has been made to solve such a problem. A main object of the present invention is to provide an electron microscope, an electron microscope operation method, an electron microscope operation program, and a computer-readable recording medium capable of arbitrarily setting a magnification of a sub-screen to facilitate a visual field search. It is in.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, an electron microscope according to claim 1 of the present invention irradiates a sample with an electron beam by applying an accelerating voltage to an electron gun based on image observation conditions and emits the electron beam from the sample. An observation image is formed by scanning a desired area of the sample surface while detecting secondary electrons or reflected electrons to be detected by one or more detectors, and the observation image is formed based on a signal detected by the detector. An electron microscope capable of displaying gradations and displaying, wherein a first display area for displaying the observation image and a first observation magnification of the observation image displayed at a predetermined timing in the first display area are provided. A setting unit for setting a second observation magnification, which is a low magnification, and capturing the observation image displayed in the first display area at the predetermined timing; and capturing the captured observation image set by the setting unit. Control for changing to 2 observation magnification A step, a storage unit for storing the observation image of the second observation magnification changed by the control unit, and a separate screen provided on the first display area, wherein the control unit changes the observation image to the second observation magnification. And a second display area for displaying the obtained observation image.
[0015]
Further, the electron microscope according to claim 2 of the present invention further changes an observation image being displayed in the first display area to a second observation magnification set by the setting section, so that the second display area is changed. And a timing setting means for designating a timing to be displayed on the display.
[0016]
Further, in the electron microscope according to claim 3 of the present invention, the setting unit sets the second observation magnification to the first observation magnification of an observation image displayed at the predetermined timing in the first display area. It is characterized by setting based on.
[0017]
Still further, in the electron microscope according to claim 4 of the present invention, the setting unit may be configured to display the observation image of the second observation magnification in the second display area at the time of the predetermined timing. The second observation magnification is set.
[0018]
Further, in the electron microscope according to the fifth aspect of the present invention, in the second display area, a portion corresponding to an area being displayed in the first display area can be clearly indicated by a frame line. I do.
[0019]
Furthermore, in the electron microscope according to claim 6 of the present invention, the observation image being displayed at the first observation magnification in the first display area is changed to the second observation magnification to perform the second display. It is characterized in that the user designates the timing of display in the area.
[0020]
On the other hand, in the method for operating an electron microscope according to claim 7 of the present invention, based on image observation conditions, an accelerating voltage is applied to an electron gun to irradiate an electron beam to a sample, and secondary electrons emitted from the sample are emitted. An observation image is formed by scanning a desired region of the sample surface while detecting electrons or reflected electrons with one or more detectors, and the observation image is expressed in gradation based on a signal detected by the detector. An operation method of an electron microscope capable of displaying an observation image at a first observation magnification in a first display area for displaying an observation image, the second observation being a magnification lower than the first observation magnification. Changing a magnification to specify a timing for displaying in the second display area separate from the first display area; and, at the specified timing, changing the observation image displayed in the first display area to the second display area. Change to observation magnification and display in the second display area Further comprising the step of storing the observation image of the second observation magnification in the storage unit.
[0021]
An electron microscope operating program according to an eighth aspect of the present invention provides an electron microscope operating program, comprising: applying an accelerating voltage to an electron gun to irradiate a sample with an electron beam based on image observation conditions; Alternatively, an observation image is formed by scanning a desired region of the sample surface while detecting the reflected electrons with one or more detectors, and the observation image is expressed in gradation based on a signal detected by the detector. An operation program for an electron microscope capable of displaying an observation image displayed at a first observation magnification in a first display area for displaying an observation image on a computer, at a predetermined timing, a magnification lower than the first observation magnification. A function of changing the second observation magnification to the second observation magnification and displaying the image in the second display area separate from the first display area, and storing the observation image changed to the second observation magnification in the storage means at the predetermined timing. With the ability to remember .
[0022]
Further, a computer-readable recording medium according to claim 9 of the present invention stores the electron microscope operation program. Recording media include magnetic disks such as CD-ROM, CD-R, CD-RW, flexible disk, magnetic tape, MO, DVD-ROM, DVD-RAM, DVD-R, DVD-RW, DVD + RW, optical disk, and optical disk. It includes a magnetic disk, a semiconductor memory, and other media capable of storing programs.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below is an example of an electron microscope for embodying the technical idea of the present invention, an operation method of the electron microscope, an electron microscope operation program, and a computer-readable recording medium, The present invention does not specify an electron microscope, an electron microscope operation method, an electron microscope operation program, and a computer-readable recording medium as follows.
[0024]
Further, the present specification does not limit the members described in the claims to the members of the embodiments. In addition, the size, the positional relationship, and the like of the members illustrated in each drawing may be exaggerated for clarity of description. Further, each element constituting the present invention may be configured such that a plurality of elements are formed of the same member and one member also serves as the plurality of elements.
[0025]
Computers, printers, external storage devices, and other peripheral devices for operations, controls, displays, and other processes connected to the electron microscope used in the embodiments of the present invention are connected to, for example, IEEE 1394 and RS-232x. And RS-422, USB, etc., for serial communication, parallel connection, or 10BASE-T, 100BASE-TX, 1000BASE-T, etc., and perform electrical communication via a network. The connection is not limited to a physical connection using a wire, but may be a wireless LAN using IEEE 802.11x or the like, a wireless connection using radio waves such as Bluetooth, infrared rays, optical communication, or the like. Further, as a recording medium for exchanging data and storing settings, a memory card, a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, and the like can be used.
[0026]
In the following embodiments, an SEM will be described. However, the present invention can also be used in TEM and other electron microscope related devices. An SEM according to an embodiment of the present invention will be described with reference to FIG. The SEM generally consists of an optical system for generating an electron beam of accelerated electrons and reaching the sample, a sample chamber in which the sample is placed, an exhaust system for evacuating the sample chamber, and an operation system for image observation. Is done. FIG. 2 shows an image diagram of a user interface screen of an operation program for operating the electron microscope. The electron microscope operation program is installed in the computer 1 of FIG. 1 and sets a user's view of an observation image shown in FIG. 2 by setting image observation conditions of the electron microscope, performing various operations, and displaying an observation image shown in FIG. 1 is displayed on the display unit 28.
[0027]
The optical system includes an electron gun 7 for generating an electron beam of accelerated electrons, a lens system for narrowing the bundle of accelerated electrons to narrow the bundle, and a detector for detecting secondary electrons and reflected electrons generated from the sample. The scanning electron microscope shown in FIG. 1 includes an electron gun 7 that irradiates an electron beam as an optical system, a gun alignment coil 9 that corrects the electron beam emitted from the electron gun 7 to pass through the center of the lens system, A condenser lens, which is a converging lens 12 for narrowing the size of the spot of the electron beam, an electron beam deflection scanning coil 18 for scanning the electron beam converged by the converging lens 12 on the sample 20, and emitted from the sample 20 with the scanning. And a backscattered electron detector 22 for detecting backscattered electrons.
[0028]
The sample chamber is provided with a sample stage, a sample introduction device, a spectroscope for X-ray detection, and the like. The sample stage has X, Y, and Z movement, rotation, and tilt functions.
[0029]
The exhaust system is necessary for the electron beam of the accelerated electrons to reach the sample without losing energy as much as possible during the passage of the gas component, and a rotary pump and an oil diffusion pump are mainly used.
[0030]
The operation system adjusts irradiation current, focuses, etc. while displaying and observing a secondary electron image, a reflected electron image, an X-ray image, and the like. For the output of secondary electron images and the like, filming with a camera was generally used if the signal was an analog signal, but in recent years it has become possible to output an image converted to a digital signal, which enables data storage, image processing, and printing. And various other processes are possible. The SEM of FIG. 1 includes a display unit 28 for displaying an observation image such as a secondary electron image or a reflected electron image, and a printer 29 for printing. Further, the operation system includes an inducing means for inducing a setting procedure of setting items necessary for setting at least an acceleration voltage or a spot size as an image observation condition.
[0031]
The SEM shown in FIG. 1 is connected to the computer 1, uses the computer 1 as a console for operating an electron microscope, saves image observation conditions and image data, and performs image processing and calculations as needed. A central processing unit 2 including a CPU and an LSI shown in FIG. 1 controls each block constituting the scanning electron microscope. By controlling the electron gun high-voltage power supply 3, an electron beam is generated from an electron gun 7 composed of a filament 4, a Wehnelt 5, and an anode 6. The electron beam 8 generated from the electron gun 7 does not always pass through the center of the lens system, and is controlled by the gun alignment coil control unit 10 so that the electron beam 8 passes through the center of the lens system. Make corrections. Next, the electron beam 8 is narrowed down by a condenser coil which is a converging lens 12 controlled by a converging lens controller 11. The converged electron beam 8 passes through an astigmatism correction coil 17 that deflects the electron beam 8, an electron beam deflection scanning coil 18, an objective lens 19, and an objective lens stop 13 that determines the beam opening angle of the electron beam 8. , To the sample 20. The astigmatism correction coil 17 is controlled by the astigmatism correction coil controller 14 to control the beam shape. Similarly, the electron beam deflection scanning coil 18 is controlled by the electron beam deflection scanning coil control unit 15, and the objective lens 19 is controlled by the objective lens control unit 16, respectively. By scanning the sample 20 with the electron beam 8, information signals such as secondary electrons and reflected electrons are generated from the sample 20, and the information signals are detected by the secondary electron detector 21 and the reflected electron detector 22, respectively. You. The detected secondary electron information signal passes through a secondary electron detection / amplification unit 23, and the backscattered electron information signal is detected by a backscattered electron detector 22 and passes through a backscattered electron detection / amplification unit 24. The data is A / D-converted by the devices 25 and 26 and sent to the image data generator 27 to be configured as image data. This image data is sent to the computer 1, displayed on a display unit 28 such as a monitor connected to the computer 1, and printed by a printer 29 as needed.
[0032]
The exhaust system pump 30 evacuates the inside of the sample chamber 31. An evacuation control unit 32 connected to the evacuation system pump 30 adjusts the degree of vacuum and controls from a high vacuum to a low vacuum according to the sample 20 and the purpose of observation.
[0033]
The electron gun 7 is a portion serving as a source for generating accelerated electrons having a certain energy, such as a W (tungsten) filament or LaB. ₆ In addition to a thermionic electron gun that emits electrons by heating a filament, there is a field emission electron gun that emits electrons by applying a strong electric field to the tip of a pointed W. The lens system is provided with a converging lens, an objective lens, an objective lens aperture, an electron beam deflection scanning coil, an astigmatism correction coil, and the like. The converging lens further converges and narrows the electron beam generated by the electron gun. The objective lens is a lens for finally focusing the electron probe on the sample. The objective lens stop is used to reduce aberration. The detector includes a secondary electron detector for detecting secondary electrons and a backscattered electron detector for detecting backscattered electrons. Since the secondary electrons have low energy, they are captured by the collector, converted into photoelectrons by the scintillator, and amplified by the photomultiplier. On the other hand, a scintillator or a semiconductor type is used for detecting the reflected electrons.
[0034]
[Sample stage]
The positioning of the observation position is performed by physically moving the sample table 33 on which the sample 20 is placed. In this case, the observation positioning means is constituted by the sample table 33. The sample stage 33 can be moved and adjusted in various directions so that the observation position of the sample 20 can be adjusted. As for the direction of movement and adjustment, in order to move and adjust the observation position of the sample stage, the sample stage can be moved in the X-axis direction, the Y-axis direction and the R-axis direction and finely adjusted. It is possible to adjust the sample stage in the T-axis direction for adjustment, and to adjust the distance (working distance) between the objective lens and the sample in the Z-axis direction.
[0035]
[Operation on Image]
The operation method of the electron microscope according to the embodiment of the present invention speeds up the frame rate in conjunction with an operation that causes a change in the observed image. Specific operations that cause a change in the image include focus adjustment, contrast adjustment, brightness adjustment, magnification adjustment, astigmatism correction, movement of the observation field, scan rotation, and the like. These operations are executed by operating respective buttons on the screen of FIG.
[0036]
[Adjust magnification]
Adjustment of the magnification is performed by the magnification button in FIG. In the example of FIG. 2, three first to third magnification buttons 53, 54, and 55 are provided. When the first magnification button 53 with a magnifying glass icon is pressed, a slider similar to the above is displayed in the sub-window, and the magnification can be continuously adjusted.
[0037]
The second magnification button 54 displays the magnification numerically. The second magnification button 54 can select a predetermined magnification from a drop-down menu, and can directly input an arbitrary magnification value as a numerical value. Even when the magnification is changed by the first magnification button 53 or the third magnification button 55, the second magnification button 54 displays the magnification of the observation image currently displayed in the first display area 47. In the example of FIG. 2, the magnification value is a relative value indicating the ratio of the size displayed in the first display area 47 to the size displayed in the second display area 48. For example, when the same image as the second display area 48 is displayed in the first display area 47, the magnification is “1”. However, the display of the magnification is not limited to this example. For example, the magnification may be displayed by an absolute magnification with the size of the sample.
[0038]
Further, when the “ultra low magnification” button as the third magnification button 55 is pressed, a predetermined minimum magnification (for example, “1”) is set. As a result, it is possible to immediately return to the display of the entire image. When the adjustment of the magnification is operated, the electron beam deflection scanning coil 18 in FIG. 1 is adjusted accordingly.
[0039]
[Moving observation field of view]
To move the observation visual field of the observation image to a desired position, the user operates the movement button 60. For moving the observation field of view, a method of physically moving the sample stage, an image shift, or the like can be used. The image shift is to move an observation field of an observation image by moving a scanning position of an electron beam. Also, the movement of the sample stage and the movement of the scanning position of the electron beam can be combined.
[0040]
In the example of FIG. 2, a method of physically moving the sample stage for positioning the observation position will be described. In FIG. 2, as the move button 60, a center move button for moving to a center position, a free button that can be freely moved to an arbitrary position, a one-screen button for enlarging and displaying a rectangular area specified by a mouse or the like on one screen, or a specified button There are four enlarged display buttons for enlarging and displaying the rectangular area. Using these buttons, it is possible to move to a desired field of view, enlarge and reduce the size, and position the observation position.
[0041]
The above positioning of the observation position is performed by physically moving the sample table 33 on which the sample is placed. According to the operation of the movement button, the sample table 33 is moved in the X direction and the Y direction. However, when moving within the range displayed in the second display area 48, display is possible without moving the sample stage.
[0042]
As described above, the positioning is not limited to this method. For example, a method of shifting the scanning position of the electron beam emitted from the electron gun can be used. Alternatively, a method using both of them can be used. Alternatively, a method of once taking in image data in a wide range and processing the data by software can also be used. In this method, since the data is once captured and processed within the data, the observation position can be moved by software, and there is no hardware movement such as movement of the sample stage or electron beam scanning. There is. As a method of capturing large image data in advance, for example, there is a method of obtaining a plurality of image data at various positions and connecting these image data to obtain image data of a wide area. Alternatively, by acquiring image data at a low magnification, a large acquisition area can be obtained.
[0043]
Further, in the screen of FIG. 2, an SEM observation ON / OFF button 70 indicating that SEM observation is ON is displayed at the upper left, and when this button is pressed, ON / OFF can be switched.
[0044]
Furthermore, a full screen display button 71 is provided at the upper right of the screen in FIG. 2, and the entire screen can be used as the area of the first display area 47.
[0045]
Next, as another embodiment of the present invention, another configuration of the display unit 28 having the first display area 47 (main screen) and the second display area 48 (sub screen) is shown in FIG. The display unit 28 shown in this figure displays a main screen for displaying an observation image being currently observed in real time as a first display area 47 and a predetermined registered image as a second display area 48 separate from the main screen. It has a sub screen. On the sub-screen, an observation image (wide-area image) obtained by acquiring and registering the observation image displayed on the main screen at a desired timing is displayed. By making the sub-screen a small screen smaller than the main screen, the area of the main screen is made large and the screen can be used efficiently. In addition, the sub screen can be changed to an arbitrary size as a separate window, can be arranged at an arbitrary place, and can have a layout according to the user's preference. Further, the main screen and the sub screen can be displayed side by side at the same time, but it is also possible to switch these screens and display them individually.
[0046]
The wide area image can be registered by a method in which a user registers a desired image at an arbitrary timing or a method in which an electron microscope automatically acquires a desired image at a preset timing. As a method for the user to manually register, for example, when the user presses a “register” button 96 on the user interface screen of FIG. 2 or FIG. 3, an observation image displayed on the main screen at that time is registered as a wide area image. You. The acquired wide area image is stored in a temporary memory of the electron microscope. It can also be transmitted to a computer and recorded on a storage element on the computer side. When only one wide area image can be registered, the image is updated by registering a new wide area image. However, it goes without saying that a plurality of wide area images can be registered by securing a required capacity of a memory area for wide area image registration. It is also possible to name the registered wide area image and save it in a predetermined image format on a hard disk or an external recording medium. The stored image can also be displayed as a thumbnail or a preview in the temporarily stored image display section 97 as “recently stored image”.
[0047]
As a method of automatically registering a wide area image at a predetermined timing, a predetermined timing is specified in advance on a setting screen. For example, it is possible to set so as to update the wide area image at predetermined time intervals such as every one minute or every five minutes, or to update the wide area image when a predetermined operation is performed. This setting can be made on the timing setting screen, and functions as timing setting means.
[0048]
When registering a wide area image, the observation magnification can be changed. For example, the image is displayed in the second display area 48 at a second observation magnification lower than the first observation magnification displayed in the first display area 47. If the image is changed to a low second observation magnification and displayed as a wide-area image, an area larger than the field of view originally displayed at the first observation magnification is registered in the second display area 48. Therefore, the visual field appears to be enlarged, and the surroundings can be observed. This method is particularly effective when searching for a visual field. This is because, when searching for a desired region to be observed, the user can know the state near the region currently being observed. In particular, since a low-magnification image whose field of view is enlarged by a single operation of pressing the “register” button 96 is displayed in the second display area 48, the user can confirm the wide field of view with a simple operation. . As in the related art, it is possible to greatly reduce the trouble of once resetting to a low magnification and confirming the state of the vicinity, and then returning to the original observation magnification again and restarting the visual field search.
[0049]
As a method of changing the observation magnification, a method in which the user directly specifies a predetermined magnification, a method in which the magnification is set in advance according to the scene, a method in which the magnification is changed in accordance with the number of registrations of the wide area image, or There is a method of designating a magnification according to the sample. A method for the user to directly specify the observation magnification is to select a desired magnification from options displayed by a drop-down menu from a registered magnification setting field 98 on the screen in FIG. 3, or increase or decrease the currently set magnification, for example. Alternatively, there is a method of directly inputting a numerical value of the magnification. The magnification may be input as a relative value between the first observation magnification and the second observation magnification, or may be configured to input the second observation magnification as an absolute value. Based on the magnification displayed in the registered magnification setting column 98, the observation image in the first display area 47 is registered and displayed in the second display area 48 as a wide area image with the observation magnification reduced. As a result, it is possible to save the trouble of resetting the original magnification again after the wide-area image is registered by reducing the observation magnification to a fraction of each time, thereby improving usability.
[0050]
As a method of setting the magnification according to the scene, a second observation magnification at the time of registration in the second display area is determined according to the first observation magnification of the observation image displayed in the first display area. Method. For example, when the first observation magnification of the observation image displayed in the first display area is the lowest magnification that can be observed or a low magnification close thereto, the first display area is displayed at that point without changing the magnification. When the first observation magnification in the first display area is a high magnification, the magnification is changed to a fraction of this observation magnification. The reason for setting in this way is that if you are observing at a low observation magnification, in general, you often observe a visual field that can be sufficiently grasped by the naked eye of the human, so register at a lower magnification than that magnification This is because the necessity is small, in other words, it is considered that registration at the same magnification is preferable. Conversely, if you are observing at a high observation magnification, it is considered that a wide area image will be registered when you lose the field of view, so the field of view is expanded compared to registration at equal magnification, in other words, observation at lower magnification Is preferred.
[0051]
Further, a method in which conditions such as a change in the observation magnification are specified in advance on a predetermined setting screen can be used. In this method, conditions for changing the observation magnification when registering the wide area image and the observation magnification itself are set in advance. As described above, in addition to determining the second observation magnification at the time of registration in the second display area 48 based on the current first observation magnification in the first display area 47, the observation magnification in the first display area 47 is determined. The user may directly specify the magnification for acquiring the wide area image regardless of the above. Further, the observation magnification and the conditions and parameters for determining the observation magnification may be changed according to the conditions. According to the conditions set here, the magnification at which the wide area image is registered at a predetermined timing is determined. This setting screen functions as a setting unit for setting the observation magnification of the observation image registered in the second display area 48.
[0052]
The relationship between the first observation magnification of the observation image being displayed in the first display area 47 and the second observation magnification of the wide area image registered in the second display area 48 is determined by the first display area 47 and the second display area 48. What is necessary is just to be able to compare with. For example, the range is 1/5 to 1/10, preferably 1/4 to 1/8. Either a method of listing preset magnifications and selecting from discrete values, or a method of continuously changing magnifications can be used. When the wide area image is displayed in the second display area 48, a frame 99 indicating which area of the second display area 48 the observation image currently displayed in the first display area 47 corresponds to is displayed in the second display area 48. Displayed above. In FIGS. 2 and 3, a rectangular frame 99 is displayed as a red line on the second display area 48, and the area inside the frame 99 is enlarged and displayed in the first display area 47. When the observation image in the first display area 47 is changed by moving the field of view or enlarging the magnification, the position and size of the frame 99 are updated accordingly.
[0053]
Furthermore, the observation magnification can be changed according to the number of registrations of the wide area image. For example, in the initial stage of visual field search, a wider visual field is secured, that is, a wide-area image is displayed at a low magnification, so that the target visual field can be easily approximated. On the other hand, it is considered that the search range of the visual field has been narrowed to some extent at the stage where the visual field searching process has advanced, so that a wide visual field is not required, in other words, it is not necessary to reduce the magnification very much. Therefore, the magnification can be suppressed to a higher value than in the initial stage. In this way, the visual field searching stage is distinguished based on the number of registrations, and the observation magnification is reduced when the number of registrations is small, and the observation magnification is increased when the number of registrations is large. Observation magnification.
[0054]
As an example, a method of displaying in the second display area 48 as the observation magnification A when initially registering a wide-area image, and as the observation magnification B when registering thereafter, based on the flowchart of FIG. explain. First, movement of the visual field and adjustment of the observation magnification are performed to search for the visual field (step S1). Next, it is determined whether registration of a wide area image is started (step S2). If the registration of the wide area image is started, the process proceeds to step S3, and if not, the process jumps to step S6.
[0055]
In step S3, it is determined whether or not the number of registrations of the wide area image is the first time. At the first time, the process proceeds to step S4A, and the observation magnification is set to A. On the other hand, in the case of the second time or later, the process proceeds to step S4B, and the observation magnification is set to B. Then, the process proceeds to step S5, where a wide area image is acquired at the set observation magnification and registered in the second display area 48. The observation image being displayed in the first display area 47 is not changed, and the observation magnification is maintained. Then, the process proceeds to step S6, where the work is terminated when the search for the visual field is completed, and the process returns to step S1 when the search is continued.
[0056]
In this example, the observation magnification A is set to the lowest settable magnification, for example, 100 times. In general, registering a wide-area image for the first time after image observation is started is before searching for a field of view, so it seems that in many cases, it is often desired to register a wide-area image at the lowest observable magnification regardless of the current observation magnification. It is. On the other hand, the observation magnification B is set to a predetermined magnification of the observation image being displayed in the first display area, for example, 1/4. At the time of the second and subsequent wide-area image registration, since the first registration is often too low in magnification or the visual field is lost when searching for the visual field, it is desirable to register at a magnification lower than the current observation magnification by a certain magnification. It is.
[0057]
The present invention is not limited thereto, and the observation magnification A may be set to be smaller than the observation magnification B. For example, the observation magnification A may be set to 1/8, and the observation magnification B may be set to 1/4. Alternatively, the observation magnification change function may be turned off in the second and subsequent registrations by setting the observation magnification B to the same magnification.
[0058]
Further, in the example of the above-described flowchart, the low magnification is set only for the first registration, and the higher magnification is set thereafter. However, the magnification may be set to be increased stepwise after the second registration. For example, 1/8 at the first registration stage, 1/4 at the second registration stage, 1/2 at the third registration stage, and the same observation image as the first display area 47 at 1 or the same magnification after the fourth registration. Is set to be registered in the second display area 48. As described above, the number of registrations and the observation magnification can be arbitrarily set.
[0059]
Furthermore, the observation magnification can be set according to the sample to be observed. If a magnification suitable for observation is roughly determined according to the sample, it may be more convenient to set the magnification to that. Therefore, the registration magnification is set in advance to a magnification corresponding to the sample to be observed, and by making the magnification callable, measurement according to the observation target can be performed, and the usability is improved.
[0060]
It is desirable that the reference point when changing the magnification be the center or the center of gravity of the first display area 47. This is because, when registered in the second display area 48, the field of view is uniformly enlarged around the second display area 48. However, it is also possible to reduce the magnification based on a corner or an arbitrary point such as the upper left or upper right of the first display area 47.
[0061]
In the above embodiment, the observation magnification changing function can be turned off, and a wide area image can be registered at the same observation magnification as the first display area 47 and displayed in the second display area 48. Needless to say.
[0062]
Functions such as the observation magnification changing function described above are executed by an electron microscope operation program transmitted to a central processing unit of the electron microscope through a computer. That is, it functions as control means for changing the observation magnification. The functions, means, and members described above can be realized virtually by software, or can be realized by being configured by physical hardware.
[0063]
As described above, in the electron microscope of the present embodiment, the observation magnification at the time of acquiring the wide area image registered in the second display area 48 is the same as the current observation image in the first display area 47, or the current observation magnification. The predetermined magnification based on the magnification or the predetermined magnification independent of the current observation magnification can be set. Further, parameters for changing the observation magnification include the current observation magnification of the first display area 47, the number of registrations of the wide area image, and the like, or the user may specify a desired magnification. When the user switches a desired magnification, a method of setting in advance which magnification is to be used in which scene on the setting screen, or one or more dedicated buttons having different magnifications and conditions are prepared, and an arbitrary A method of switching a magnification by pressing a desired button at a scene or timing can be used. As an example of the method of using the dedicated button, three types of buttons are prepared for the same magnification, a predetermined magnification, and an arbitrary magnification described above, and a predetermined condition or magnification is set or assigned to each button in advance. Then, the user can register a wide area image at a desired magnification by selecting and pressing each button.
[0064]
【The invention's effect】
As described above, the electron microscope, the electron microscope operating method, the electron microscope operating program, and the computer-readable recording medium of the present invention are registered on the second display area according to the image observation conditions and conditions of the observation image. It is possible to switch the magnification of the image to be performed. This makes it possible to display a wide area image more suitably than the image being displayed in the first display area by a simple operation, and it is possible to easily search for a visual field by displaying these images side by side or by switching them. it can.
[0065]
This is because the present invention does not fix the magnification at the time of registration in the second display area to the magnification currently displayed in the first display area, but changes the magnification to an optimum magnification according to conditions. . Thus, an appropriate image can be registered on another screen without worrying about the current observation magnification, and registered at an easy-to-use magnification. In particular, if the image is displayed in the second display area at a magnification lower than the observation magnification of the observation image being displayed in the first display area, a wider area including peripheral images not displayed in the first display area is obtained. Therefore, the visual field is apparently widened, which is extremely convenient for searching for the target visual field. In addition, a wide area can be acquired more easily and without troublesome operations than the conventional technique, so that the user is convenient. In particular, for an electron microscope that can be displayed at a high magnification and has a wide dynamic range, searching for a point of view is important, so the function of the present invention is extremely useful.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a scanning electron microscope according to one embodiment of the present invention.
FIG. 2 is an image diagram showing an example of a user interface screen of an electron microscope operation program according to one embodiment of the present invention.
FIG. 3 is an image diagram showing an example of a user interface screen of an electron microscope operation program according to another embodiment of the present invention.
FIG. 4 is a flowchart showing a procedure for searching for a visual field in an electron microscope according to still another embodiment of the present invention.
[Explanation of symbols]
1 ... Computer
2 Central processing unit
3. High voltage power supply for electron gun
4 ... filament
5 ... Wehnelt
6 ... Anode
7 ... Electron gun
8 ... Electron beam
9 ... gun alignment coil
10 ... gun alignment coil controller
11: Convergent lens controller
12 ・ ・ ・ Convergent lens
13 ... objective lens aperture
14 ... Astigmatism correction coil control unit
15 ... Electron beam deflection scanning coil controller
16 Objective lens control unit
17 ・ ・ ・ Astigmatism correction coil
18 ... Electron beam deflection scanning coil
19 ... Objective lens
20 ... sample
21 ... Secondary electron detector
22 ... backscattered electron detector
23 ... Secondary electron detection amplifier
24 ... backscattered electron detection and amplification unit
25 ... A / D converter
26 ... A / D converter
27 ... Image data generation unit
28 Display unit
29 ・ ・ ・ Printer
30 ... Exhaust pump
31 ・ ・ ・ Sample room
32 ... Exhaust control unit
33 ... Sample stage
47 ... first display area
48 second display area
49 ... Tip screen
50 ... wide area image
51 ... e preview
53 ... first magnification button
54 ... second magnification button
55 ... third magnification button
60 ... Move button
70 SEM observation ON / OFF button
71 ... full screen display button
96 ... "Registration" button
97 ... temporary storage image display field
98 ・ ・ ・ Registered magnification setting field
99 ... frame line

Claims (9)

Based on the image observation conditions, an accelerating voltage is applied to the electron gun to irradiate the sample with an electron beam, and secondary electrons or reflected electrons emitted from the sample are detected by one or more detectors while a desired surface of the sample is detected. An electron microscope that forms an observation image by scanning an area, and is capable of displaying the observation image in gradation based on a signal detected by the detector,
A first display area for displaying the observation image;
A setting unit for setting a second observation magnification that is lower than the first observation magnification of the observation image displayed at a predetermined timing in the first display area;
Control means for capturing the observation image displayed in the first display area at the predetermined timing, and changing the captured observation image to a second observation magnification set by the setting unit;
Storage means for storing the observation image of the second observation magnification changed by the control means,
An electron microscope comprising: a second display area provided on a separate screen from the first display area and displaying an observation image changed to a second observation magnification by the control unit. The electron microscope further comprises:
A timing setting unit for changing an observation image being displayed in the first display area to a second observation magnification set by the setting unit and designating a timing for displaying the observation image in the second display area. The electron microscope according to claim 1, wherein The apparatus according to claim 1, wherein the setting unit sets the second observation magnification based on the first observation magnification of an observation image displayed at the predetermined timing in the first display area. Electron microscope. The said setting part sets the said 2nd observation magnification based on the frequency | count of displaying the observation image of the said 2nd observation magnification in the said 2nd display area at the time of the said predetermined timing, The said 1st or 2nd characterized by the above-mentioned. 2. The electron microscope according to 2. The electron microscope according to any one of claims 1 to 4, wherein the electron microscope enables a portion corresponding to an area being displayed in the first display area to be clearly indicated by a frame line in the second display area. microscope. In the electron microscope, a user designates a timing at which an observation image being displayed at the first observation magnification in the first display area is changed to the second observation magnification and displayed in the second display area. The electron microscope according to claim 1, wherein: Based on the image observation conditions, an accelerating voltage is applied to the electron gun to irradiate the sample with an electron beam, and secondary electrons or reflected electrons emitted from the sample are detected by one or more detectors while a desired surface of the sample is detected. An observation image is formed by scanning an area, and an operation method of an electron microscope capable of displaying and displaying the observed image in gradation based on a signal detected by the detector,
The observation image displayed at the first observation magnification in the first display area for displaying the observation image is changed to a second observation magnification that is lower than the first observation magnification, and is separately provided from the first display area. Specifying the timing of display in the second display area of
At the designated timing, the observation image displayed in the first display area is changed to a second observation magnification and displayed in the second display area, and the observation image at the second observation magnification is stored in storage means. Memorizing step;
The operation method of the electron microscope provided with. Based on the image observation conditions, an accelerating voltage is applied to the electron gun to irradiate the sample with an electron beam, and secondary electrons or reflected electrons emitted from the sample are detected by one or more detectors while a desired surface of the sample is detected. An operation program for an electron microscope capable of forming an observation image by scanning an area, displaying the observation image in gradation based on a signal detected by the detector, and displaying the observation image on a computer. The observation image displayed at the first observation magnification in the first display area is changed to the second observation magnification that is lower than the first observation magnification at a predetermined timing, and the observation image is separately provided from the first display area. A function to be displayed in the second display area of
A function of storing the observation image changed to the second observation magnification in the storage unit at the predetermined timing;
Electron microscope operation program for realizing A computer-readable recording medium storing the electron microscope operation program according to claim 8.

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