WO2015068670A1 - Dispositif de faisceaux de particules chargées - Google Patents

Dispositif de faisceaux de particules chargées Download PDF

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Publication number
WO2015068670A1
WO2015068670A1 PCT/JP2014/079155 JP2014079155W WO2015068670A1 WO 2015068670 A1 WO2015068670 A1 WO 2015068670A1 JP 2014079155 W JP2014079155 W JP 2014079155W WO 2015068670 A1 WO2015068670 A1 WO 2015068670A1
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Prior art keywords
sample
charged particle
particle beam
image
electron image
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PCT/JP2014/079155
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English (en)
Japanese (ja)
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美樹 土谷
康平 長久保
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株式会社日立ハイテクノロジーズ
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Publication of WO2015068670A1 publication Critical patent/WO2015068670A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/261—Details
    • H01J37/265—Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/20—Positioning, supporting, modifying or maintaining the physical state of objects being observed or treated
    • H01J2237/2001—Maintaining constant desired temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/245—Detection characterised by the variable being measured
    • H01J2237/24571—Measurements of non-electric or non-magnetic variables
    • H01J2237/24585—Other variables, e.g. energy, mass, velocity, time, temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2802—Transmission microscopes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2803—Scanning microscopes characterised by the imaging method
    • H01J2237/2804—Scattered primary beam
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2803—Scanning microscopes characterised by the imaging method
    • H01J2237/2806—Secondary charged particle
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/26—Electron or ion microscopes
    • H01J2237/28—Scanning microscopes
    • H01J2237/2809—Scanning microscopes characterised by the imaging problems involved

Definitions

  • the present invention relates to a charged particle beam apparatus, and more particularly to a method and apparatus suitable for maintaining a good frozen state of an observation sample.
  • a chemical fixing method using a reducing agent such as glutaraldehyde as a fixing solution
  • a physical fixing method that immediately stops movement by rapid freezing and maintains the structure at that time.
  • the chemical fixation method the tissue is stained with heavy metal, so the structure can be observed with clear contrast, but the protein contained in the sample may be destroyed and the original structure of the biological tissue cannot be captured.
  • the physical fixation method requires a special freezing apparatus, but there is no artifact formation by a staining agent or the like, and the original structure of a biological tissue can be maintained.
  • the ice embedding method is a kind of rapid freezing of electron microscopy, and is a technique in which a sample is rapidly frozen and observed with an electron microscope at a cryogenic temperature without being fixed or stained.
  • Samples such as living organisms, foods and polymers containing water in the tissue are put into liquefied ethane cooled with liquid nitrogen, rapidly frozen at a cooling rate of 10 4 ° C / sec or more, and embedded in amorphous ice Observe the prepared sample.
  • Amorphous ice formed in a thin film can be used as a support for observation without fixing, dyeing or drying.
  • Patent Document 1 Japanese Patent Laid-Open No. 2013-88328
  • a TEM is used after rapid freezing in order to accurately observe the original tissue structure of a liquid sample such as food.
  • Non-patent document 1 describes a technique for performing TEM using the ice embedding method.
  • the TEM and STEM described in these documents use a high acceleration voltage of 80 kV to 300 kV.
  • a sample When observing a liquid sample or biological cell containing water with a charged particle beam device, a sample is prepared using a pretreatment method such as a rapid freezing method. At this time, the sample is placed on a sample holder that can be maintained in a frozen state and introduced into the charged particle beam apparatus.
  • a frozen sample or a cooled sample produced by the ice embedding method uses a TEM observation dedicated device or a STEM observation dedicated device. Electron beams and X-rays with various information are emitted from the sample due to the interaction between the incident electron beam and the sample, but the TEM image and STEM image detect inelastically scattered electrons or elastically scattered electrons that have passed through the sample. is doing. Therefore, information on the sample surface cannot be obtained.
  • FIG. 1A is a schematic diagram of a normal ice-embedded sample and a schematic diagram of the observation result.
  • the structure 103 is included in the amorphous ice 102 while maintaining the original structure.
  • SE secondary electron image
  • SE secondary electron image
  • a secondary electron image shows the surface of amorphous ice, and uneven information expressed as a change in contrast cannot be obtained.
  • the structure 103 can be confirmed by a difference in contrast.
  • the amorphous ice may be sublimated or melted, and the structure that should be contained may be exposed on the surface (FIG. 1).
  • Such a sample is not suitable for observing an ice-embedded sample because the exposed portion of the structure is directly irradiated with an electron beam, causing electron beam damage. In this case, in the secondary electron image 105, unevenness information is detected by the exposed structure and appears as a difference in contrast.
  • the obtained information is information that has passed through the sample and is observed with the same contrast as that of a normal ice-embedded sample, and the suitability of the ice-embedded sample cannot be determined. .
  • the sample is encapsulated in amorphous ice, but frost 108 may adhere to the surface.
  • the frost 108 on the surface is shown with a changed contrast. Therefore, whether the frost is attached or not in the sample only by the observation of the bright field image and the dark field image. It is difficult to determine whether the structure is originally present. Even in such a case, it is desirable to perform surface observation with a secondary electron image.
  • Patent Document 2 Japanese Patent Application Laid-Open No. 2004-214065 discloses a mechanism capable of detecting a transmission electron (dark field signal) having a large scattering angle, which was difficult to detect, and selecting a range of the scattering angle in SEM. And obtaining a high contrast STEM image.
  • a signal obtained from the observation visual field is arbitrarily selected and displayed one by one. Therefore, for example, when acquiring a bright field image, a dark field image, and a secondary electron image, it is necessary to scan the observation field with an electron beam three times and detect a signal.
  • Patent Document 3 Japanese Patent Laid-Open No. 7-169429
  • a diaphragm for a bright field image and a diaphragm for a dark field image are held on a common diaphragm base, and a darkness is detected by one detector by switching the diaphragm position.
  • An observation method is disclosed by switching between a visual field signal and a bright field signal. Since the diaphragm is switched by moving it in and out on the optical axis, it is impossible to observe a bright field image and a dark field image at the same time. Therefore, in order to acquire a bright field image and a dark field image, each signal must be acquired by scanning the electron beam twice. Considering thermal damage caused by electron beams, frozen samples and ice-embedded samples are vulnerable to heat, so it is desirable that the number of electron beam scans for acquiring images be smaller.
  • the problem to be solved by the present invention is to provide a sample observation apparatus capable of observing a frozen sample such as a biological sample, food, and water-containing material with an electron microscope while ensuring a good frozen state.
  • the optical system includes: an optical system that irradiates a sample with primary electrons and scans the sample; a detection system that detects electrons obtained based on the irradiation; and a vacuum chamber.
  • a charged particle beam apparatus having a control device for forming and storing an image based on the electrons detected by the detection system, and a cooling source for cooling the sample, and maintaining the cooled state
  • the detection system Is a secondary electron detector that detects secondary electrons generated from the sample by scanning the primary electron beam, and non-scattered electrons among the transmitted electrons generated by scattering of the primary electron beam in the sample, With inelastically scattered electrons
  • a bright-field signal detector for detecting, among the transmission electron has a dark-field signal detector for detecting a non-elastically scattered electrons, and transmission electron detector composed of, a.
  • At least three kinds of signals of a secondary electron image, a bright-field image as a transmission electron image, and a dark-field image can be observed simultaneously for observing a frozen sample.
  • the influence of thermal damage can be reduced.
  • frost adheres to the surface of an ice-embedded sample, it can be determined that it is frost by simultaneously observing at least three types of signals. Therefore, the cold trap position, vacuum degree, and holder temperature can be adjusted. Is possible.
  • a frozen sample prepared by an ice embedding method or the like can be stably observed while maintaining a good frozen state.
  • 1 is a schematic configuration diagram illustrating an embodiment of the present invention. It is a figure which shows the function of the main operation and image processing control part by this invention. It is a flowchart explaining the quality determination process of the sample by simultaneous observation. It is a schematic diagram of the normal sample produced by the ice embedding method. It is a flowchart explaining the removal process of frost.
  • FIG. 2 is a schematic diagram illustrating a configuration example of a scanning electron microscope apparatus capable of observing an STEM image according to the embodiment of the present invention.
  • an electron beam 202 emitted from a field emission electron gun 201 is accelerated by an anode 204 by an electric field formed by an extraction electrode 203 to which a voltage is applied, is focused by a first focusing lens 205, and is The lens diaphragm 206 removes unnecessary areas of the beam.
  • the electron beam 202 that has passed through the objective lens stop 206 is narrowed down by the second focusing lens 207 and the objective lens 210. Further, the focused electron beam 202 is scanned two-dimensionally on the sample by the deflection coil 208.
  • Electrons that pass through the sample are divided into bright field signal electrons 214 that are not scattered or inelastically scattered in the sample and dark field signal electrons 212 that are elastically scattered.
  • the scattering field of the bright field signal electrons 214 is limited by the bright field stop 215, and only the bright field signal electrons transmitted through the stop are detected by the bright field signal detector 216.
  • the dark field signal electrons 212 are scattered in the sample, the dark field signal electrons 212 pass through the sample at a certain angle and are detected by the dark field signal detector 213 disposed below the objective lens.
  • the dark field signal detector 213 operates so as to obtain an appropriate contrast in the vertical direction where the sample and the bright field stop 215 are located.
  • the dark field signal detector 213 is controlled when, for example, the user selects the dark field signal detector control button 815 shown in FIG. 8 so that an appropriate contrast can be obtained while checking the dark field image on the display 218.
  • the position control signal is transmitted to the device 217, and the dark field signal detector 213 is moved.
  • the electron beam 202 scans the sample
  • electrons in the sample are excited by inelastic scattering of incident electrons, and the electrons emitted into the vacuum are called secondary electrons.
  • the secondary electron detector 209 that detects secondary electrons, the surface shape of the sample can be observed as a secondary electron image.
  • the secondary electrons include reflected electrons having the composition information of the sample.
  • Signals obtained from the secondary electron detector 209, the bright field signal detector 216, the dark field detector 213, and the like are sent to the image processing control unit 225 included in the control device 217 to perform image processing and to display an image. Is displayed on the display 218.
  • the vacuum sample chamber has a cold trap 220 and a position adjusting mechanism 219 for moving the tip position of the cold trap.
  • the tip position can be adjusted according to the degree of vacuum and the state of frost attached to the frozen sample. Is possible.
  • the sample chamber is provided with a vacuum gauge 221 for measuring the degree of vacuum, and the measured degree of vacuum is sent to the image processing control unit 225 provided in the control device 217.
  • the sample cooling holder 222 includes a cooling source container 223 that stores a cryogenic cooling source such as liquid helium, liquid nitrogen, and slush nitrogen, and can hold the sample fixed to the tip of the holder frozen by heat conduction.
  • a heater that can set the holder temperature to an arbitrary temperature is provided, and the temperature adjustment can be changed by the temperature adjustment mechanism 224.
  • the temperature of the sample cooling holder 222 is sent to the image processing control unit 225 provided in the control device 217.
  • the sent measurement result is displayed on the display 218.
  • FIG. 3 is a diagram for explaining functions and processing of the image processing control unit 225 of FIG.
  • the image processing control unit 225 determines whether the frozen sample is in an appropriate frozen state, and controls the vacuum atmosphere for stable observation of the frozen sample.
  • a frozen sample such as an ice-embedded sample is fixed to the sample cooling holder 222 and introduced into a scanning electron microscope at a temperature at which the frozen state can be maintained, for example, between ⁇ 90 ° C. and ⁇ 170 ° C.
  • the sample cooling holder 222 is introduced, the holder temperature, the degree of vacuum, and the current position of the cold trap tip are measured, and the results are input to the image processing control unit 225.
  • the holder temperature, the degree of vacuum, and the cold trap position are input to the holder temperature adjustment unit 301, the vacuum degree measurement unit 302, and the cold trap position adjustment unit 303, respectively, and are calculated by the optimum condition calculation unit 305 based on the measurement results. Is done.
  • the optimum condition calculation unit 305 obtains conditions for the holder set temperature, the degree of vacuum, and the cold trap position for maintaining an appropriate degree of vacuum and sample temperature. For example, along the saturated vapor pressure curve of water described in Non-Patent Document 2, when the sample temperature is ⁇ 100 ° C., the degree of vacuum is set to 1 ⁇ 10 ⁇ 5 Torr.
  • the calculation result obtained by the optimum condition calculation unit 305 is input to the holder temperature adjustment unit 301, the vacuum degree measurement unit 302, and the cold trap position adjustment unit 303 again.
  • a new set temperature is transmitted from the holder temperature adjusting unit 301 to which the calculation result is input to the temperature adjusting mechanism 224 of the holder, and the sample cooling holder temperature is reset to an appropriate temperature.
  • a new set position is transmitted to the cold trap position adjusting mechanism 219 from the cold trap position adjusting unit 303 to which the calculation result is inputted, and the tip of the cold trap is set to an appropriate position.
  • the stage position setting unit 304 measures the stage position so that the cold trap position and the sample do not interfere with each other. If there is an interference, a warning is displayed on the display 218 via the display display setting unit 313.
  • the image processing control unit 225 also performs a determination as a reference for performing various processes based on observation of an image formed from at least three detection signals.
  • the secondary electron image calculation unit 306 receives the signal obtained by the secondary electron detector 209
  • the bright field image calculation unit 307 receives the signal obtained by the bright field signal detector 216.
  • the dark field image calculation unit 308 receives a signal obtained by the dark field signal detector 213.
  • the image processing control unit 225 includes an acquired image calculation unit 310 that performs image processing for determining whether a frozen sample is normally frozen from each obtained image.
  • the acquired image calculation unit 310 performs image processing and comparison from the simultaneously obtained secondary electron image and transmission electron image. For example, edge detection processing is performed on both images, the unevenness information is extracted, the amount of the extracted position that coincides in both images is calculated, and it is determined whether the sample is exposed from amorphous ice depending on the size.
  • template matching techniques such as a normalized correlation method and a phase-only correlation method can be used to evaluate the similarity between both images and apply the determination to suitability of the sample.
  • the charged particle beam irradiation amount calculation unit 311 measures the electron beam irradiation amount while continuing to observe the same field of view without changing the observation magnification after moving the stage. For example, the observation of the same visual field is continued, and at a certain point in time, the amount of electron beam irradiation when the sample state becomes inappropriate due to sublimation or melting of amorphous ice can be stored, and the observable time can be calculated.
  • the observable time is displayed on the display 218 via the display display setting unit 313.
  • the signals are displayed on the image or the display, recorded in the recording unit 314, or a certificate so that the simultaneous acquisition can be recognized. Etc. are issued as data.
  • a certificate indicating that different types of signals have been simultaneously acquired is issued by the certificate issuance setting unit 312 via an output unit (not shown). This certificate is saved at the same time as the acquired image is saved in the recording unit 314.
  • the acquired secondary electron signal and transmission electron signal are simultaneously displayed on the display 218 by the display display setting unit 313.
  • the display level setting unit 313 can display the degree of vacuum, the sample cooling holder temperature, the cold trap temperature, and whether the sample is normal on the display 218.
  • the recording unit 314 records the simultaneously acquired image and certificate, the cold trap and stage position at the time of image acquisition, the measured degree of vacuum, and the sample cooling holder temperature.
  • FIG. 4 shows a process of simultaneously acquiring the secondary electron signal, the bright field signal, and the dark field signal to determine whether the quality of the ice-embedded sample or the frozen sample is appropriate.
  • the frozen sample is fixed at a temperature at which the frozen state can be maintained by the sample cooling holder, for example, between ⁇ 90 ° C. and ⁇ 170 ° C., and introduced into the electron microscope. Thereafter, the stage is moved to move the field of view to an arbitrary sample position (step 401). Next, a primary electron beam is scanned on the sample, and a secondary electron image, a bright field image, and a dark field image are simultaneously acquired (step 402). The obtained three types of signals are sent to the image processing control unit 225 of FIG. 3 and displayed on the display 218. At the same time, it is determined whether or not an appropriate ice embedding state is obtained by image processing (step 403). (Step 404).
  • step 403 If it is determined by the image processing (step 403) that the sample is normally embedded in ice, the primary electron beam is continuously scanned, and three types of signals are simultaneously captured (step 405) and converted into an image. Appears on the display. The image at this time is stored (step 406).
  • steps 406 when different types of signals are captured at the same time, they are displayed on an image or display, recorded in the recording unit 314, or as data such as a certificate so that it can be recognized that they have been acquired simultaneously. publish.
  • the process returns to step 401 and the conditions for acquiring the image are adjusted by moving the stage.
  • step 407 when the photographer continues observation, it is possible to continue photographing with the same field of view or a different field of view. If the observation is not continued, the process ends (step 407).
  • FIG. 5 shows a schematic diagram of a sample prepared by the ice embedding method.
  • a structure 503 such as a cell, bacteria, polymer, or food is dissolved in a solvent such as water is used, it is frozen into amorphous ice 502 by a technique such as rapid freezing.
  • the structure 503 whose surroundings are covered with amorphous ice is not exposed on the surface and exists inside the amorphous ice 502 (upper view in FIG. 5).
  • a secondary electron signal, a bright field signal, and a dark field signal are obtained.
  • the secondary electron signal is acquired by a detector and converted into an image, the surface is covered with amorphous ice, so that there is no unevenness and a secondary electron image 505 having a relatively uniform contrast is obtained.
  • the bright field signal or the dark field signal is converted into an image, the contrast of the structure inside the amorphous ice is obtained as an image.
  • the bright-field image 506 among the electrons that have passed through the sample, electrons that are transmitted without being scattered and electrons that are scattered at a small angle are detected and imaged.
  • the bright-field image 506 is bright.
  • the part that appears in contrast and causes diffraction is observed in dark contrast.
  • the dark field image 507 since only a specific diffracted wave is transmitted and detected among the transmitted electrons, the portion causing the diffraction is bright, and the portions other than the portion causing the diffraction and the amorphous portion are compared with it. Looks dark. In general, in the bright field image, the portion where the structure exists is observed dark, and the amorphous ice portion appears bright, whereas in the dark field image, the portion where the structure exists appears bright and the amorphous ice portion appears. The part often looks dark.
  • the secondary electron signal has no irregularities, so an image with uniform contrast is obtained.
  • the contrast of the contained structure is A sticky image is obtained.
  • Image processing at this time is performed by the image processing control unit 225. As a result, in this case, it is determined as a normal frozen sample, and observation can be continued.
  • a certificate is issued and stored as an image or text data. Further, the display 218 displays that the sample state is appropriate.
  • FIG. 6 is a flowchart showing a method for dealing with a case where frost adheres to the sample surface after the frozen sample is introduced into the electron microscope.
  • frost is removed by performing processing according to the flowchart as shown in FIG.
  • the frozen sample is fixed at a temperature at which the frozen state can be maintained by the sample cooling holder and introduced into the electron microscope. Thereafter, in order to move the visual field to an arbitrary sample position, stage movement is performed (step 601). Next, in order to confirm the sample state, a secondary electron image, a bright field image, and a dark field image are simultaneously acquired (step 602). The obtained three types of signals are sent to the image processing control unit 225 of FIG. 3 and displayed on the display 218. At the same time, it is determined whether or not frost is attached by image processing (step 603) (step 604). ).
  • the three types of signals are simultaneously observed and photographed (step 610).
  • the stage may be moved (step 601) and observation may be continued with a different field of view. If the imaging is not continued, the process is terminated and the sample cooling holder is removed.
  • the temperature of the sample cooling holder 222 (28) is raised to a temperature at which the frost sublimates at the measured degree of vacuum according to the water vapor pressure curve (step 605).
  • the water vapor pressure curve it is described in Non-Patent Document 2 and the like as described above.
  • the curve is stored in the control device 217 and the set temperature is automatically obtained. Alternatively, the user can input the set temperature based on the curve.
  • the tip position of the cold trap 220 is moved (step 607).
  • the cold trap 220 adsorbs and traps water vapor remaining in the atmosphere in the sample chamber or water vapor generated from the sample by sublimation to the cooled metal. By bringing the tip position closer to the sample, moisture sublimated from the sample is efficiently adsorbed.
  • step 608 the degree of vacuum is detected again (step 608), and if the degree of vacuum has returned to the level before the sample temperature rise (step 605), the temperature of the sample cooling holder 222 is lowered so that the sample temperature is suitable for observation.
  • An image for checking the surface of the sample is acquired again (step 602). If frost is attached, the processes from step 602 to step 609 are performed.
  • a certificate 701 in FIG. 7A is a schematic diagram showing an example of a certificate issued by the certificate issuance setting unit 312 shown in FIG. As described above, the same content can be displayed and recorded on an image or a display without issuing a certificate.
  • the system version of the image processing control unit 225 the model name of the electron microscope, the product number of the electron microscope, the serial number of the image, the date and time of shooting, and the number given to a set of images taken simultaneously.
  • the name of the photographer is entered in the issuer column.
  • the shooting date and time, shooting area, etc. can be described.
  • This certificate has a read-only function added so that it cannot be edited or appended after it is issued.
  • the name of the photographer is distinguished and entered by the name of each user and the individual system logged in with a password when the electron microscope is activated.
  • the image serial number is recorded as a serial number of the simultaneous observation images that have been taken so far and cannot be changed.
  • FIG. 7B shows an example in which a symbol is added as information to the acquired image.
  • the model name, the observation condition acceleration voltage, the observation magnification, the detection signal, and the information 703 are recorded at the bottom of the image.
  • information such as a character string, an image, a symbol, or the like indicating that one part of the image (1/3) is a part of the image Record.
  • FIG. 8 is a diagram showing an example of display on the display when three types of signals are acquired.
  • the screen 801 of the display 218 includes an area for simultaneously displaying the secondary electron image 802, the bright field image 803, and the dark field image 804.
  • condition display unit 805 the cooling temperature of the sample cooling holder 222, the tip position of the cold trap 220, and the value of the degree of vacuum detected by the vacuum gauge 221 are displayed.
  • setting unit 806 a value obtained by setting the sample cooling holder temperature to an arbitrary temperature is displayed on the set temperature button 807. If the cold trap position is also set to an arbitrary position, it is displayed on the input value position setting button 808.
  • the operation instruction unit 809 displays a sample frozen state determination instruction unit 810 that determines a sample frozen state and a frost adhesion determination instruction unit 811 that determines frost adhesion.
  • a sample frozen state determination instruction unit 810 that determines a sample frozen state
  • a frost adhesion determination instruction unit 811 that determines frost adhesion.
  • the frost adhesion determination instruction unit 811 When the frost adhesion determination instruction unit 811 is selected, the flowchart shown in FIG. 6 is performed. When it is determined that the frost is adhered, the frost adhesion button is switched to a warning display until the frost adhesion is improved.
  • the image acquisition instructing unit 813 When the image acquisition instructing unit 813 is selected, three types of signals can be acquired simultaneously, or only one type or four types of images can be acquired arbitrarily.
  • the instruction of the signal selected by the image acquisition instruction unit 813 is transmitted to the image acquisition switching unit 309 and executed.
  • the screen area of the current condition display unit 805, the setting unit 806, and the operation instruction unit 809 is switched to image display, and four types of display can be performed simultaneously.
  • the end button 814 is selected to end a series of cryo observations.
  • Example 8 In order to understand the three-dimensional structure of a structure contained in a thin film sample, a tomography method is known. In this method, a TEM image and a STEM image are continuously photographed while tilting the sample at a high angle (maximum tilt angle: 60 ° to 80 °), and a three-dimensional thin film sample is obtained from the obtained series of continuous tilt images. It is a method to reconstruct information. Although several tens or more continuous tilt images are acquired, the larger the number, the more the sample is subjected to thermal damage due to the electron beam. However, since it is usually based on transmission image observation such as a TEM image or STEM image, it is difficult to catch deformation and alteration due to thermal damage on the sample surface. Therefore, we propose a method for tomography using secondary electron signals while monitoring for deformation and alteration of the sample.
  • secondary electron signals can be simultaneously acquired by one electron beam scanning. For example, at least three types of signals are acquired simultaneously at each angle, but if the sample is embedded in amorphous ice, the secondary electron signal obtained by tilting the sample is uneven at any angle. Information is not observed. When the frozen sample is deformed by heat during the continuous tilt image acquisition, the secondary electron signal includes the uneven information of the deformed portion, and it can be seen that the sample is deformed. By comparing the secondary electron image obtained simultaneously with the acquisition of the continuous tilt image with the images before and after the image acquisition, deformation or alteration of the sample surface can be recognized.
  • the sample frozen state on the display 218 is switched to a warning display.
  • Such determination of sample quality can also be performed in the sample frozen state determination instruction unit 810 of FIG. With such a mechanism, even while performing tomography of a frozen sample or an ice-embedded sample, it is possible to perform observation while maintaining the quality of the sample appropriately.
  • Example 9 By receiving electron beam damage, a frozen sample or an ice-embedded sample may be deformed or deteriorated. Because of electron beam irradiation while searching for a field of view to obtain an image by observation, the sample may already be deformed at the time of observation. Therefore, simultaneous observation is performed while searching for the visual field, and the acquired image data is continuously acquired, recorded, and stored as a moving image. Thereby, the observation image of the normal sample before the sample deformation can be extracted after the observation is completed.
  • Certificate issuance setting unit 313 Display display setting unit 314: Recording unit 701: Example of certificate indicating simultaneous acquisition of different types of signals 702: Acquired image 703 ... Example of information displayed in acquired image 801 ... Screen 805 ... Condition display unit 806 ... Setting unit 807 ... Set temperature button 808 ... Input value position setting button 809 ... Operation instruction section 810 ... Sample frozen state determination instruction section 811 ... Frost adhesion determination instruction section 812 ... Sample position button 813 ... Image acquisition instruction section 814 ... End button 815 ... ⁇ Dark field signal detector control button

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  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

La présente invention concerne un dispositif de faisceaux de particules chargées et fournit un procédé et un dispositif appropriés pour maintenir un bon état congelé d'un échantillon d'observation. Le dispositif de faisceaux de particules chargées obtient : une image d'électrons secondaires (505) formée par la détection d'électrons secondaires générés à partir de l'échantillon en balayant un faisceau d'électrons primaires ; une image d'électrons de champ clair (506) formée par la détection de signaux de champ clair parmi les électrons de transmission générés par le faisceau d'électrons primaires qui est diffusé à l'intérieur de l'échantillon ; et une image d'électrons de champ sombre (507) formée par la détection de signaux de champ sombre. L'état de l'échantillon refroidi à l'intérieur d'une chambre à vide est déterminé sur la base des informations d'images obtenues. Les conditions d'observation de l'échantillon sont ajustées sur la base des résultats de la détermination.
PCT/JP2014/079155 2013-11-07 2014-11-04 Dispositif de faisceaux de particules chargées WO2015068670A1 (fr)

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JP2013230781A JP6353646B2 (ja) 2013-11-07 2013-11-07 荷電粒子線装置及び当該装置を用いた試料の観察方法
JP2013-230781 2013-11-07

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WO2017098574A1 (fr) * 2015-12-08 2017-06-15 株式会社日立ハイテクノロジーズ Piège anti-contamination, son procédé de commande et dispositif à faisceau de particules chargées
JP7382299B2 (ja) 2020-09-30 2023-11-16 日本電子株式会社 荷電粒子線装置

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JPH06208841A (ja) * 1991-09-20 1994-07-26 Hitachi Ltd 走査電子顕微鏡のクライオ装置
JPH09196831A (ja) * 1996-01-19 1997-07-31 Hitachi Ltd 試料冷却観察装置
JP2002083564A (ja) * 2000-09-05 2002-03-22 Hitachi Ltd 微小部分析装置及び分析方法
JP2005158288A (ja) * 2003-11-20 2005-06-16 Canon Inc 電子顕微鏡用試料冷却ホルダ
JP2007299753A (ja) * 2006-05-01 2007-11-15 Fei Co 温度スイッチを備える粒子−光学装置
JP2008034231A (ja) * 2006-07-28 2008-02-14 Hitachi High-Technologies Corp 電子顕微鏡装置
JP2008204642A (ja) * 2007-02-16 2008-09-04 Hitachi High-Technologies Corp 走査透過荷電粒子線装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06208841A (ja) * 1991-09-20 1994-07-26 Hitachi Ltd 走査電子顕微鏡のクライオ装置
JPH09196831A (ja) * 1996-01-19 1997-07-31 Hitachi Ltd 試料冷却観察装置
JP2002083564A (ja) * 2000-09-05 2002-03-22 Hitachi Ltd 微小部分析装置及び分析方法
JP2005158288A (ja) * 2003-11-20 2005-06-16 Canon Inc 電子顕微鏡用試料冷却ホルダ
JP2007299753A (ja) * 2006-05-01 2007-11-15 Fei Co 温度スイッチを備える粒子−光学装置
JP2008034231A (ja) * 2006-07-28 2008-02-14 Hitachi High-Technologies Corp 電子顕微鏡装置
JP2008204642A (ja) * 2007-02-16 2008-09-04 Hitachi High-Technologies Corp 走査透過荷電粒子線装置

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