WO2023243063A1 - 透過型荷電粒子ビーム装置、及びロンチグラム撮像方法 - Google Patents

透過型荷電粒子ビーム装置、及びロンチグラム撮像方法 Download PDF

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Publication number
WO2023243063A1
WO2023243063A1 PCT/JP2022/024228 JP2022024228W WO2023243063A1 WO 2023243063 A1 WO2023243063 A1 WO 2023243063A1 JP 2022024228 W JP2022024228 W JP 2022024228W WO 2023243063 A1 WO2023243063 A1 WO 2023243063A1
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WIPO (PCT)
Prior art keywords
sample
piezo element
ronchigram
imaging
focal position
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Ceased
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PCT/JP2022/024228
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English (en)
French (fr)
Japanese (ja)
Inventor
輝 石澤
雄大 久保
美智子 鈴木
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Hitachi High Tech Corp
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Hitachi High Tech Corp
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Priority to PCT/JP2022/024228 priority Critical patent/WO2023243063A1/ja
Priority to US18/866,838 priority patent/US20250336641A1/en
Priority to JP2024528048A priority patent/JPWO2023243063A1/ja
Publication of WO2023243063A1 publication Critical patent/WO2023243063A1/ja
Anticipated expiration legal-status Critical
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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
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
    • H01J37/153—Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators
    • 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
    • H01J37/02—Details
    • H01J37/20—Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
    • 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
    • H01J37/02—Details
    • H01J37/22—Optical, image processing or photographic arrangements associated with the tube
    • H01J37/222—Image processing arrangements associated with the tube
    • 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
    • H01J2237/153—Correcting image defects, e.g. stigmators
    • H01J2237/1534—Aberrations

Definitions

  • the present disclosure relates to a transmission charged particle beam device and a Ronchigram imaging method.
  • the aberration corrector the positive third-order spherical aberration generated within the electron optical system can be canceled out by the negative third-order spherical aberration generated using the multipole lens. This enables high-resolution, high-contrast imaging.
  • the structure of a general aberration corrector is configured using multiple multipole lenses, multiple transfer lenses, and multiple adjustment lenses.
  • Patent Document 1 states, ⁇ Two circular lenses with the same focal length are placed between the first sexter pole and the second sexter pole, and It is stated that the two circular lenses are arranged at twice the distance, and further spaced from a plane passing through the center of the sexter pole adjacent to each circular lens at a distance corresponding to the focal length of the circular lens.
  • Patent Document 2 describes two-fold symmetrical third-order star aberration (S3) and A technique for independently correcting rotationally symmetric third-order astigmatism (A3) is disclosed.
  • the control signals given to the multipole lens, deflection lens, and transfer lens are adjusted to reduce the aberration.
  • the Ronchigram method may be used as one of the means for checking aberrations.
  • the Ronchigram method is a method of irradiating a sample with a focused electron beam and checking an image (Ronchigram) that reflects the angular distribution of aberrations created by the electron beam that has passed through the sample.
  • each aberration is corrected, and the objective lens focus is changed from the back focus to the front focus by changing the objective lens current, and judging from the degree of change, it is determined whether the aberration remains. If so, perform aberration correction again. Then, the above-described correction is repeated until it is determined that each aberration has disappeared.
  • aberration correction can be performed while visually confirming each aberration sequentially.
  • the number of times the flow is performed becomes extremely large, and it takes a long time until all the aberrations are corrected.
  • Patent Document 3 describes a method of measuring aberrations using a Ronchigram (hereinafter referred to as a focus variation Ronchigram) in which the positional relationship between the focal point and the sample is slightly varied during imaging of one Ronchigram. is disclosed.
  • a Ronchigram hereinafter referred to as a focus variation Ronchigram
  • Example 2 of Patent Document 3 the minute displacement of the focal point is not caused by excitation of the objective lens, but a method of displacing the sample height is used, and in particular, a piezo element is used as a means for displacing the sample height.
  • a method of displacing the sample height is used, and in particular, a piezo element is used as a means for displacing the sample height.
  • An example of its use is disclosed.
  • piezo elements have faster response to applied signals than actuators using motors, they are highly compatible as a replacement for objective lenses as a means of moving a focal point in multiple cycles. Further, alternating current operation is required to change the focus, and since this operation works to suppress displacement creep of the piezo element, it is possible to improve the accuracy of displacement by the piezo element.
  • electromagnetic means are used to displace the positional relationship between the focus and the sample in the step of imaging a focus variation Ronchigram.
  • Example 3 of Patent Document 3 discloses a method of displacing the positional relationship between the focus and the sample using a piezo element in the process of imaging a focus variation Ronchigram.
  • this method there is no problem when imaging a focus variation Ronchigram because it is driven by an AC signal, but when imaging a single Ronchigram or a focus variation Ronchigram at multiple positions, the focus may be affected by the displacement hysteresis of the piezo element. Accuracy cannot be improved due to the positional relationship with the sample.
  • the piezo element has a large displacement creep, and in an operation in which movement and stopping are repeated, it is necessary to wait for Ronchigram imaging until the displacement creep stops, so it takes time to capture a plurality of Ronchigram images.
  • Patent Document 3 describe the use of a plurality of focus variation Ronchigrams for the purpose of increasing the accuracy of aberration measurement. As described in Patent Document 3, this results in an increase in the number of measurements, and even a single focus variation Ronchigram requires multiple periods of focus variation, resulting in a significant increase in the time required to measure aberrations.
  • the first problem is that displacement accuracy cannot be improved due to magnetic hysteresis.
  • the second problem is that the amount of heat generated changes as the current in the lens coil used to change the focus changes, causing temperature drift in the field of view and focus due to thermal expansion and contraction of electron microscope components.
  • the third problem is that since there is a time constant for changes in the magnetic flux of the lens coil, it takes time to capture multiple Ronchigram images.
  • the following problem occurs when the positional relationship between the focal point and the sample is displaced using a piezo element.
  • the fourth problem is that displacement accuracy cannot be improved due to the effect of displacement hysteresis of the piezo element.
  • the fifth problem is that it takes time to image multiple Ronchigrams due to displacement creep of the piezo element.
  • the present disclosure provides a transmission charged particle beam device and a Ronchigram imaging method that can solve the five problems described above.
  • a transmission charged particle beam device of the present disclosure acquires a Ronchigram of a sample and corrects aberrations, and includes a piezo element that displaces the sample by expanding and contracting. a position detection element that detects the position of the sample; a control unit that controls the amount of expansion and contraction of the piezo element based on the position of the sample detected by the position detection element, displaces the sample, and stops the sample; and an imaging unit that images one or more single Ronchigrams without changing the focal position of the beam irradiated onto the sample while the sample is stopped.
  • the positional relationship between the focus and the sample can be displaced with high precision and at high speed.
  • FIG. 2 is a schematic diagram of a transmission-type charged particle beam device of Examples 1 to 5.
  • FIG. 2 is a plan view showing details of the stage in FIG. 1;
  • FIG. 2 is a side view showing details of the stage of FIG. 1;
  • FIG. 4 is a block diagram showing details of the piezo element control unit of FIG. 2 or 3.
  • FIG. 5 is a block diagram showing a modification of the piezo element control unit of FIG. 4.
  • FIG. FIG. 3 is a diagram illustrating the positional relationship between a focus and a sample according to Example 1.
  • 2 is a graph showing a method of controlling a Z piezo element with a Z position sensing element when acquiring a plurality of single Ronchigrams according to Example 1.
  • FIG. 7 is a diagram illustrating the thickness of a sample and the positional relationship between the focus and the sample according to Example 2.
  • 7 is a graph showing a method of controlling a Z piezo element with a Z position sensing element when acquiring a plurality of single Ronchigrams according to Example 2.
  • 12 is a graph related to a method of controlling each piezo element with a position sensing element when acquiring a plurality of single Ronchigrams according to Example 3.
  • FIG. 7 is a diagram illustrating the thickness of a sample and the positional relationship between the focus and the sample according to Example 2.
  • 7 is a graph showing a method of controlling a Z piezo element with a Z position sensing element when acquiring a plurality of single Ronchigrams according to Example 2.
  • 12 is a graph related to a method of controlling each piezo element with a position sensing element when acquiring a plurality of single Ronchigrams according to Example 3.
  • FIG. 7 is a diagram showing the relationship between the imaging position and the retracted position of a single Ronchigram according to Example 3; 7 is a graph related to a method of controlling each piezo element with a position sensing element when acquiring a plurality of single Ronchigrams according to Example 4.
  • FIG. 7 is a diagram showing imaging positions of a plurality of single Ronchigrams according to Example 4;
  • FIG. 7 is a diagram illustrating the positional relationship between a tilted focal point and a sample according to Example 5.
  • FIG. 7 is a plan view showing details of a modified example of the stage of Examples 1 to 5. 17 is a side view showing details of a stage according to a modification of FIG. 16.
  • the X direction, Y direction, and Z direction described in this application intersect with each other and are orthogonal to each other.
  • the Z direction will be described as the vertical direction, height direction, or thickness direction of a certain structure.
  • expressions such as “plan view” or “planar view” used in this application mean that a plane constituted by the X direction and the Y direction is viewed from the Z direction.
  • Expressions such as “cross-sectional view” or “cross-sectional view” refer to a plane that includes quantity components in the Z direction and the X direction, or in the Y direction, or in the XY direction.
  • a transmission electron microscope or a scanning transmission electron microscope whose stage is entered from the side will be used as an example of a charged particle beam device.
  • the present invention is not limited to type electron microscopes, nor is it limited to those in which the stage is entered from the side.
  • Example 1 ⁇ Structure of transmission charged particle beam device 1> The transmission charged particle beam device of Example 1 will be described below with reference to FIG. In the first embodiment, a side entry type transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) is shown as an example of the transmission type charged particle beam device 1.
  • the transmission charged particle beam device 1 of the first embodiment acquires a Ronchigram of a sample and automatically or manually corrects aberrations.
  • the transmission-type charged particle beam device 1 includes an electron gun 4, an electron optical system 5, an imaging system 6, and a stage 3 for displacing a sample, and these are integrated.
  • a vacuum is maintained within the lens barrel of the transmission-type charged particle beam device 1 using a vacuum evacuation means (not shown).
  • Primary electrons 22 are emitted from the electron source 7.
  • the primary electrons 22 are focused and accelerated using the suppression electrode 8, extraction electrode 9, and anode 10 in the electron gun 4. Thereafter, the primary electrons 22 are expanded or contracted and deflected by the focusing lens 11 and the deflection lens 12 in the electron optical system 5. Thereafter, the primary electrons 22 are enlarged, reduced, shifted, tilted, etc. by an aberration corrector 40 to correct aberrations. Thereafter, the focus of the primary electrons 22 is adjusted by the objective lens 13. The primary electrons 22 are then irradiated onto the sample placed on the sample holder 16 at the tip of the stage rod 15.
  • Signal electrons 23 are generated from the sample irradiated with the primary electrons 22 by reflection and emission of secondary electrons. Signal electrons 23 are detected by detector 19 .
  • the signal output from the detector 19 is processed by the signal processing unit 36, then processed (imaged) by the image processing unit 33B and CPU 33A in the computer 33, and displayed on the display device 33C.
  • the electrons that have transmitted through the sample are reduced or enlarged by the imaging system 6 and are irradiated onto the fluorescent screen 18.
  • fluorescence 25 is generated from the fluorescent screen 18.
  • the generated fluorescence 25 is detected by the camera 20 (imaging section).
  • the signal output from the camera 20 is processed by the signal processing unit 36, then processed (imaged) by the image processing unit 33B and CPU 33A in the computer 33, and displayed on the display device 33C.
  • the transmission-type charged particle beam device 1 may include detectors such as a charged particle beam detector, an optical detector, a camera, and an X-ray detector (not shown), and an aperture related to these detectors. It may also include a mechanism or the like.
  • the stage 3 includes a stage drive mechanism 14, a stage rod 15, and a sample holder 16.
  • a sample holder 16 is connected to the tip of the stage rod 15. The sample is placed on the sample holder 16.
  • the position of the field of view is changed by driving the stage 3.
  • the stage drive mechanism 14 is operated in response to a command from the stage control unit 35, and the stage rod 15 is pushed, pulled, rotated, sent, etc. These movements may be realized via atmospheric pressure or spring force, or by offsetting pre-applied atmospheric pressure or spring force.
  • the stage drive mechanism 14 includes a piezo element and a position detection element.
  • the control device 2 (control unit) includes a computer 33, a main control unit 34, a stage control unit 35, a signal processing unit 36, and an aberration corrector control unit 41.
  • the control device 2 controls each component of the transmission charged particle beam device 1 .
  • the computer 33 can be configured by a computer with a known configuration.
  • the computer 33 includes calculation means for performing calculations, storage means for storing information, and input/output means for inputting and outputting information.
  • the storage means includes, for example, non-transitory storage media.
  • the storage means can store programs. By the arithmetic means executing this program, the computer 33 realizes the operations described in this specification. Accordingly, the transmission-type charged particle beam device 1 realizes the operation described in this specification. That is, this program causes the transmission charged particle beam device 1 to execute the method described in this specification.
  • the calculation means includes a CPU 33A and an image processing unit 33B
  • the input/output means includes a display device 33C
  • the storage means includes a memory 33D as a storage medium.
  • the computer 33 can perform calculations related to signals and transmit and receive information (commands, etc.) to and from each device.
  • the computer 33 also serves as an interface with people and other electronic devices.
  • the main control unit 34 includes an amplifier, an analog-to-digital converter, a digital-to-analog converter, various types of logic, etc., and supplies signals, power, and voltage to the electron gun 4, electron optical system 5, imaging system 6, camera 20, stage 3, etc. give. Further, the main control unit 34 receives signals and performs various processing and control.
  • the main control unit 34 also includes a plurality of memories that store programs for controlling each memory, and one or more CPUs and FPGAs that perform processing. The CPU and FPGA communicate with the computer 33 and control each using instructions from the computer 33 or results of calculations within the CPU.
  • the stage control unit 35 receives instructions regarding movement, rotation, tilting, etc. of the stage 3 from the computer 33 or the main control unit 34, and controls the stage drive mechanism 14. Although not shown here, the stage control unit 35 includes a piezo driver and a position sensing element control unit.
  • the aberration corrector control unit 41 controls a large number of magnetic poles and electrodes included in the aberration corrector 40, and performs an aberration correction operation.
  • the Ronchigram imaged by the camera 20 is processed by the signal processing unit 36 or the image processing unit 33B, and the user observes what is displayed and recognizes the aberration. Then, the user adjusts the aberration corrector control unit 41 to perform an aberration correction operation.
  • the image processing unit 33B calculates aberrations, and based on the results, the computer 33 automatically sends a command to the aberration corrector control unit 41 to perform an aberration correction operation.
  • FIG. 2 is a plan view showing details of the stage 3 in FIG. 1. Details of the stage operation in the X direction and the Y direction will be explained using FIG. 2.
  • An X actuator 52, a Y actuator 53, and a stage rod insertion mechanism 60 are installed in the lens barrel 50.
  • the stage rod 15 is inserted into the lens barrel 50 through the stage rod insertion mechanism 60.
  • An X piezo element 54 and an X position detection element 70 are attached to the tip of the X actuator 52.
  • a Y piezo element 55 and a Y position detection element 71 are attached to the tip of the Y actuator 53.
  • the X piezo element 54, the Y piezo element 55, and the Z piezo element 65 which will be described later, expand and contract by an amount corresponding to the applied voltage, thereby displacing the sample.
  • each of the X position detection element 70, the Y position detection element 71, and the Z position detection element 72 detects the absolute position of the sample displaced by the X piezo element 54, the Y piezo element 55, and the Z piezo element 65. .
  • the X actuator 52 and the X piezo element 54 are pressurized by the X support 61 to support the stage rod 15.
  • the Y actuator 53 and the Y piezo element 55 are pressurized by the Y support 62 and support the stage rod 15.
  • the stage 3 uses the X actuator 52 and the X piezo element 54 to move the stage rod 15 and sample holder 16 in the X direction 57. Further, the stage 3 uses the Y actuator 53 and the Y piezo element 55 to move the stage rod 15 and the sample holder 16 in the Y direction 58.
  • sample holder 16 is connected to the tip of the stage rod 15.
  • a sample 59 is placed on the sample holder 16 .
  • Sample 59 is an observation target. Further, sample 59 includes an amorphous thin film necessary for obtaining a Ronchigram.
  • relatively coarse displacements (hereinafter referred to as coarse movements) are performed by the X actuator 52 and the Y actuator 53.
  • relatively small displacements (hereinafter referred to as fine movements) are performed by the X piezo element 54 and the Y piezo element 55.
  • the displacement of the sample by the X piezo element 54 and the Y piezo element 55 is determined by the amount of expansion and contraction due to the piezoelectric effect of the X piezo element 54 and the Y piezo element 55, respectively, by the X position detection element 70 and the Y position detection element 71. This is done with feedback.
  • Coarse movement and fine movement are realized as movements such as pushing, pulling, rotating, and feeding the stage rod 15 and sample holder 16, for example. These movements may be realized via atmospheric pressure or spring force, may be realized by offsetting atmospheric pressure or spring force applied in advance, or may be realized via a lever not shown. .
  • the stage control unit 35 controls the X actuator 52, the Y actuator 53, the X piezo element 54, and the Y piezo element 55.
  • the stage control unit 35 includes a stage operation calculation unit 35A, a motor driver 35B, and a piezo element control unit 35C.
  • FIG. 3 is a side view showing details of stage 3 in FIG. 1. Details of the stage operation in the Z direction will be explained using FIG. 3. Note that the objective lens 13 is not shown to avoid complexity.
  • FIG. 3 shows a Z actuator 64 for moving the stage 3 in a Z direction 66 parallel to the irradiation direction of the primary electrons 22, a Z piezo element 65, and a Z position detection element 72.
  • the stage 3 uses a Z actuator 64 and a Z piezo element 65 to move the stage rod 15 and sample holder 16 in the Z direction 66.
  • the Z actuator 64 like the X actuator 52 and the Y actuator 53, performs coarse movement of the sample
  • the Z piezo element 65 like the X piezo element 54 and the Y piezo element 55, performs fine movement of the sample.
  • the Z actuator 64 and the Z piezo element 65 are pressurized by the Z support 63 to support the stage rod 15.
  • the Z piezo element 65 whose displacement is controlled by the Z position detection element 72 and the piezo element control unit 35C, changes the distance between the focal point and the sample when capturing a plurality of single Ronchigram images during aberration correction.
  • Examples of the X position detection element 70, the Y position detection element 71, and the Z position detection element 72 include a range finder using capacitance, a range finder using a laser, a linear encoder, and a strain gauge. Ru.
  • Each of the X support 61, Y support 62, and Z support 63 is made of various materials, such as a spring, a reverse action spring, a leaf spring mechanism, hard rubber, and atmospheric pressure.
  • the transmission charged particle beam device 1 may further include a Tilt axis and an Azimuth axis (axes for tilting the sample with respect to the beam) (not shown), and may also include a Rotation axis for rotating the sample itself.
  • FIG. 4 is a block diagram showing details of the piezo element control unit 35C of FIG. 2 or 3.
  • the piezo element control unit 35C is provided for each of the X piezo element 54, the Y piezo element 55, and the Z piezo element 65.
  • the piezo element control unit 35C that controls the amount of displacement of the Z piezo element 65 will be described. Note that the piezo element control unit that controls the amount of displacement of the X piezo element 54 and the piezo element control unit that controls the amount of displacement of the Y piezo element 55 are the same as the piezo element control unit 35C, so a description thereof will be omitted.
  • the computer 33 or the aberration corrector control unit 41 instructs the stage operation calculation unit 35A to determine the amount of displacement by the Z piezo element 65.
  • the stage operation calculation unit 35A commands the amount of displacement to the digital-to-analog converter 105 in the piezo element control unit 35C, and inputs an analog signal to the comparator 104.
  • Comparator 104 outputs an analog signal to piezo driver 103.
  • the piezo driver 103 applies a voltage to the Z piezo element 65 according to the output from the comparator 104.
  • the Z piezo element 65 to which a voltage is applied expands and contracts by an amount of expansion and contraction that corresponds to the applied voltage.
  • the amount of expansion/contraction is detected by the Z position detection element 72, and a signal such as a voltage, charge, current, pulse, or frequency corresponding to the amount of expansion/contraction is output.
  • the signal output from the Z position sensing element 72 is converted and amplified by the position sensing element signal processor 102 into a signal format (for example, voltage) that is easy to process, and is input to the comparator 104.
  • the comparator 104 compares the signal of the digital-to-analog converter 105 and the signal output from the position sensing element signal processor 102, and the signal of the position sensing element signal processor 102 is the voltage (command value) of the digital-to-analog converter 105. If there is a difference between the two, the signal output from the comparator 104 is changed so as to eliminate the difference.
  • the piezo element control unit 35C is a displacement analog feedback of the Z piezo element 65 using the Z position detection element 72.
  • the analog-to-digital converter 106 plays the role of always inputting the output of the Z position detection element 72 to the stage operation calculation unit 35A. Based on the output of the analog-to-digital converter 106, the stage operation calculation unit 35A checks whether the displacement amount of the Z piezo element 65 has reached the target value and whether the Z piezo element 65 is statically fixed. You can check.
  • FIG. 5 is a block diagram showing a modification of the piezo element control unit of FIG. 4.
  • the signal output from the analog-to-digital converter 106 is compared and calculated with the target displacement amount within the stage operation calculation unit 35A, without using an analog comparator. Expressed simply, this is displacement digital feedback.
  • the Z position detection element 72 detected the amount of expansion and contraction of the Z piezo element 65. However, if the Z position detection element 72 can detect the absolute amount of displacement of the sample by the Z piezo element 65, The method is not limited to one that detects the amount of expansion and contraction.
  • FIG. 6 is a diagram illustrating the positional relationship between the focus and the sample according to Example 1.
  • the axis 120 indicating the distance L [nm] has a unit of [nm] and indicates the distance between the focus of the beam and the sample.
  • the focal point and sample positional relationship schematic diagram 121 includes a beam trajectory schematic diagram 125 and a sample 126, and the focal point position of the beam trajectory schematic diagram 125 is fixed at a position 0 nm from the axis 120. At this time, the distance L1 (127) between the focal point and the sample is ⁇ 100 nm, which indicates the back focal point.
  • the distance L2 (128) between the focus and the sample is 0 nm, which indicates a positive focus.
  • the distance L3 (129) between the focus and the sample is +25 nm indicating the front focus.
  • the distance L4 (130) between the focus and the sample is +150 nm indicating the front focus.
  • the focus of the beam is fixed and the position of the sample 126 is determined using a Z piezo sensor equipped with a Z position detection element 72, as shown in schematic diagrams 121 to 124 of the positional relationship between the focus and the sample. element 65 to change the distance between the focal point and the sample.
  • a Z piezo sensor equipped with a Z position detection element 72, as shown in schematic diagrams 121 to 124 of the positional relationship between the focus and the sample. element 65 to change the distance between the focal point and the sample.
  • FIG. 7 is a graph showing a method of controlling the Z piezo element 65 with the Z position detection element 72 when acquiring a plurality of single Ronchigrams according to the first embodiment.
  • the vertical axis 151 of the graph 150 is the distance between the focus and the sample (L focus-sample [nm]), and the horizontal axis 152 is the time (Time [ms]).
  • 0 nm on the vertical axis indicates a positive focus.
  • the positive region on the vertical axis is the front focus
  • the negative region on the vertical axis is the back focus.
  • the value of the vertical axis (distance L between the focus and the sample) is the same as the amount of displacement of the stage 3 caused by the Z piezo element 65 and the Z position detection element 72.
  • T piezo move 155 shown in a graph 154 that enlarges the enlarged area 153 in the graph 150 indicates the time from the start of displacement to the time when the Z piezo element 65 becomes static
  • T expose 156 indicates the time taken when a single Ronchigram is imaged. Indicates the exposure time of the camera.
  • the position of the focus and the sample can be changed step by step by repeating the operation of moving the sample to a specified position in the time T piezo move 155 and capturing the Ronchigram in the time T exposure 156. , and multiple single Ronchigrams are imaged each time the sample is stopped.
  • the time required for the displacement and stabilization of the Z piezo element 65 with the Z position detection element 72 is 30 msec, and the exposure time of the camera when imaging a single Ronchigram is 70 msec. It becomes possible to image 10 single Ronchigrams.
  • FIG. 8 is an example of imaging a plurality of single Ronchigrams according to the first embodiment.
  • R1, R2, R3, and R4 are the single Ronchigrams at the back focus
  • R5 is the single Ronchigram at the positive focus
  • R6, R7, R8, R9, and R10 are the single Ronchigrams at the front focus.
  • All images of R1 to R10 or any single Ronchigram of R1 to R10 are processed by the image processing unit 33B, and aberration information is extracted at the distance between each focal point and the sample. It becomes possible to calculate aberrations.
  • Example 1 A configuration in which a plurality of single Ronchigrams having different distances between a focal point and a sample are imaged using a Z piezo element 65 with a Z position sensing element 72 according to the first embodiment, and a Z piezo element with a Z position sensing element 72 According to the control method No. 65, the following effects can be obtained.
  • the fourth problem of "displacement accuracy is not improved due to the effect of displacement hysteresis of the piezo element" can be solved, the displacement accuracy can be increased, and the accuracy of aberration calculation can be improved.
  • Example 2 Control method of Z piezo element 65 with Z position detection element 72 (Example 2)> It is known that if the focus of the beam remains within the amorphous thin film contained in the sample, the amorphous thin film will be damaged. Therefore, the time the beam remains focused within the amorphous thin film must be kept to a minimum. Therefore, in the second embodiment, when displacing the sample so as to pass through the focal position, the sample is displaced without stopping at least within the range where the focal position falls on the sample.
  • Example 2 when the sample is displaced so as to pass through the focal position, at least within the range where the focal position enters the sample, the moving speed is faster than the moving speed of the sample before or after the focal position of the beam enters the sample. Displace the sample with
  • FIG. 9 is a diagram illustrating the relationship between the thickness of the sample and the distance between the focal point and the sample according to Example 2.
  • the distance between the focus of the beam focused in the sample 126 (including the amorphous thin film) and the sample is D sens-L 132 on the back focus side and D sens-U 131 on the front focus side.
  • D sens-L 132 and D sens-U 131 are both the same as the thickness of the sample.
  • the sum of these two values is taken as D sens 158, and this is defined as a region where the amorphous thin film is likely to be damaged.
  • the area where the focus falls within the sample is defined as the area where the amorphous thin film is likely to be damaged. The closer the amorphous thin film is, the more damage will occur to the amorphous thin film.
  • FIG. 10 is a graph showing a method of controlling the Z piezo element 65 with the Z position detection element 72 when acquiring a plurality of single Ronchigrams according to the second embodiment.
  • the meanings of the vertical axis 151 and the horizontal axis 152 are the same as in FIG. 7, so their explanation will be omitted.
  • D sens 158 indicates a region where the amorphous thin film is likely to be damaged particularly during Ronchigram imaging in the distance between the focal point and the sample, which is the vertical axis 151.
  • the displacement of the sample by the Z piezo element 65 is determined at predetermined time intervals as in FIG. Repeat and stop, and image a single Ronchigram during the stopped time.
  • the distance between the focal point and the sample falls into the region of D sens 158, damaging the amorphous thin film and reducing the quality of the Ronchigram. descend. Therefore, when the distance between the focal point and the sample falls within the area of D sens 158 using the Z piezo element 65 with the Z position detection element 72, the sample is moved as fast as possible to move the sample to the area of D sens 158. Minimize the length of stay. That is, the moving speed when displacing the sample in the region of D sens 158 is faster than the moving speed when displacing the sample outside the region of D sens 158.
  • the deterioration in the quality of the Ronchigram refers to a decrease in the contrast of the Ronchigram, artifact information of the amorphous thin film entering the Ronchigram, and the like.
  • the Z piezo element 65 with the Z position detection element 72 repeats displacement and stopping of the sample, and images a Ronchigram at the time of stopping.
  • the time required to displace the Z piezo element 65 with the Z position detection element 72 is 30 msec, and the exposure time of the camera when imaging a single Ronchigram is 70 msec, 10 Ronchigrams can be imaged in 1 second. can be carried out while reducing damage to the amorphous thin film by minimizing the stay time in the D sense 158 region.
  • Ronchigrams are acquired, but the operation of moving at high speed in the region of D sens 158 may be performed simply when accompanied by a movement that straddles the front focus and the back focus. do not have.
  • the sixth issue is that when crossing the front and back focal points, the sample position stays near the positive focus for a long time due to the effect of the time constant of the lens coil. There is also the problem that this damages the amorphous thin film and causes a decline in the quality of the Ronchigram.
  • FIG. 11 is a graph related to a method of controlling each piezo element with a position detection element when acquiring a Ronchigram according to the third embodiment.
  • a graph 150 showing the relationship between time and the distance between the focus and the sample quickly moves through the region of D sens 158 where damage to the amorphous thin film is likely to occur, similar to FIG.
  • each of the vertical axis 151 and the horizontal axis 152 in FIG. 11 is the same as in FIG. 10, so the explanation thereof will be omitted.
  • the time scale is in the range from 400 msec to 900 msec.
  • the vertical axis 161 of a graph 160 showing the relationship between travel distance on the XY plane and time is the travel distance on the XY plane
  • the horizontal axis 162 is time as in FIGS. 7 and 10. .
  • T esc 162 indicates the evacuation time during which the sample was evacuated from the beam irradiation position.
  • the moving distance in the XY plane means the moving distance when the X piezo element 54 is used alone, the moving distance when the Y piezo element 55 is used alone, or the moving distance when the X piezo element 54 and the Y piezo element 54 are used alone.
  • the outer product of the amount of movement when both elements 55 are used may also be used.
  • the displacement in the retracting direction may be performed using the X actuator 52 or the Y actuator 53 without using the piezo element.
  • FIG. 12 is a diagram showing the relationship between the imaging position and the retracted position of a single Ronchigram according to the third embodiment.
  • FIG. 12 simulates the XY plane on the sample, and the units of both the vertical and horizontal axes are nm.
  • Point EXP 165 on the XY plane is a place to stay when capturing a Ronchigram, and Point ESC 166 is a place to stay at evacuation time T esc 162 in FIG. 11.
  • Point EXP 165 and Point ESC 166 have different coordinates, and are characterized in that their beam irradiation ranges do not overlap when they are at each other's positions.
  • Example 2 the Z piezo element 65 moves quickly in the region of D sens 158, but since the beam is irradiated to the imaging location of the Ronchigram on the sample, the amorphous thin film is damaged to some extent, and the Ronchigram is This leads to quality deterioration.
  • the area on the sample to which the beam is irradiated is changed using the X piezo element 54, the Y piezo element 55, or both before entering the D sens 158 area where damage is likely to occur on the amorphous thin film. be done. Thereafter, the area on the sample that is irradiated with the beam is returned to its original position.
  • Example 3 Before entering the region of D sens 158, which is the distance between the focal point and the sample where damage to the amorphous thin film is likely to occur, the region hit by the beam is changed using the X piezo element 54, the Y piezo element 55, or both. By returning the Ronchigram to the imaging position after leaving the area, deterioration in quality of multiple single Ronchigrams can be avoided. This leads to the sixth problem, ⁇ When crossing the front and back focal points, the time constant of the lens coil causes the sample position to stay near the positive focus for a long time, which can damage the amorphous thin film. Solving the problem of "resulting in deterioration in the quality of Ronchigram". Other effects are the same as in Example 1.
  • FIG. 13 is a graph related to a control method when acquiring a Ronchigram of each piezo element with a position detection element according to the fourth embodiment.
  • the meanings of the vertical axis, horizontal axis, and graph are the same as in FIG. 11, so their explanation will be omitted.
  • Embodiment 3 in addition to the time T esc 162 for staying at the evacuation position, the time required to reach the evacuation position and the time from the evacuation position to the imaging position are required. It takes longer to capture an image.
  • the amorphous thin film will be damaged to some extent no matter the distance between the focal point and the sample. This means that as the number of single Ronchigrams to be imaged increases, the quality of the Ronchigrams deteriorates.
  • the X piezo element 54 with the X position detection element 70 and the Y piezo element 55 with the Y position detection element 71 move the sample.
  • the displacement is performed, and the Ronchigram is always imaged at a different position of the amorphous thin film.
  • FIG. 14 is a diagram showing the imaging positions of a plurality of single Ronchigrams according to the fourth embodiment.
  • the coordinates of the first imaging location P8, the ninth imaging location P9, and the tenth imaging location P10 are different from each other, and the beam irradiation ranges at the imaging locations P1 to P10 do not overlap. It is a characteristic.
  • all the imaging locations were different from each other, but it is also conceivable that the same location may be imaged multiple times, for example, twice or three times, within the number of times that would cause less damage to the amorphous thin film.
  • the imaging position of the Ronchigram is different each time, so the amorphous thin film is required to be as uniform as possible and to move accurately in the XY plane on the order of several nanometers.
  • FIG. 15 is a diagram illustrating the positional relationship between the tilted sample and the focal point according to Example 5.
  • the movement of the X piezo element 54 and the Y piezo element 55 allows movement from the front focal point to the rear focal point. Utilizing this movement, it is possible to change the distance between the focal point and the sample as shown in FIG. 10 by moving on the XY plane using the X piezo element 54 and the Y piezo element 55.
  • Example 5 The same effect as in Example 4 can be achieved without using the Z piezo element 65 with the Z position detection element 72.
  • the stage device configuration is such that an annular coarse movement stage is displaced by a coarse movement mechanism arranged concentrically, and a toroidal fine movement stage is displaced using a piezo element with a position detection element arranged concentrically.
  • a configuration that allows The details of this configuration will be explained below using FIGS. 16 and 17.
  • FIG. 16 A plan view of the stage and its surroundings in this configuration is shown in FIG. 16, and a cross-sectional view is shown in FIG. 17. Note that parts with the same functions are denoted by the same reference numerals as in FIGS. 1, 2, and 3, and the description thereof will be omitted.
  • the stage in this configuration is divided into a fine movement stage member 81 and a coarse movement stage member 82, each of which has an annular shape. Further, the center of the ring of the fine movement stage member 81 and the center of the ring of the coarse movement stage member 82 each substantially coincide with the optical axis.
  • the coarse movement stage member 82 is fixed in the X direction and the Y direction by the X actuator 52, the X coarse movement support 61A, the Y actuator 53, and the Y coarse movement support 62A.
  • the line connecting the operating axes of the X actuator 52 and the X coarse movement support 61A and the line connecting the action axes of the Y actuator 53 and the Y coarse movement support 62A are at 90 degrees, and the light They are spread out in concentric circles around the axis.
  • the fine movement stage member 81 is fixed by the X piezo element 54 with the X position detection element 70, the X fine movement support 61B, the Y piezo element 55 with the Y position detection element 71, and the Y fine movement support 62B.
  • What is the line that connects the operating axes of the X piezo element 54 with the X position detection element 70 and the X fine movement support 61B, and the line that connects the action axes of the Y piezo element 55 with the Y position detection element 71 and the Y fine movement support 62B? ideally at 90 degrees, and spread concentrically around the optical axis.
  • the Z direction of the coarse movement stage member 82 is fixed by the Z actuator 64 and the Z coarse movement support 72A. Further, the fine movement stage member 81 is fixed in the Z direction by the Z piezo element 65 with the Z position detection element 72 and the Z fine movement support 72B.
  • the sample exchange flange 83 is opened, the sample holder 16 is recovered using the sample exchange device 80, and after the sample exchange, it is placed on the fine movement stage member 81 again by the sample exchange device 80. After the sample exchange operation, the sample exchange flange 83 is closed, and the sample exchange device 80 is separated from the sample holder 16. This feature keeps the sample holder 16 in vacuum and isolated from atmospheric pressure. This reduces image vibration due to changes in atmospheric pressure and the influence of drift due to thermal expansion of the sample holder 16 itself due to changes in temperature, compared to a side entry type sample holder.
  • the transmission charged particle beam device 1 equipped with the stage 3 is a scanning/transmission electron microscope (STEM/TEM).
  • a charged particle beam device is a scanning electron microscope (SEM), a combination device of a scanning ion microscope and a scanning electron microscope (FIB-SEM), or a device that applies these, and It may be an apparatus capable of processing, analyzing, and inspecting samples.
  • the transmission charged particle beam device 1 of the first embodiment includes not only the Z piezo element 65 but also the X piezo element 54 and the Y piezo element 55 for displacing the sample. If the displacement in the direction can be controlled with high precision, it is not necessary to provide the X piezo element 54, the Y piezo element 55, and their peripheral devices.
  • the positional relationship between the focal point and the sample can be changed without using the Z piezo element 65, so the Z piezo element 65 and its peripheral devices do not need to be provided.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
PCT/JP2022/024228 2022-06-16 2022-06-16 透過型荷電粒子ビーム装置、及びロンチグラム撮像方法 Ceased WO2023243063A1 (ja)

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US18/866,838 US20250336641A1 (en) 2022-06-16 2022-06-16 Transmission Charged Particle Beam Device and Ronchigram Imaging Method
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Citations (3)

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Publication number Priority date Publication date Assignee Title
US6552340B1 (en) * 2000-10-12 2003-04-22 Nion Co. Autoadjusting charged-particle probe-forming apparatus
JP2008270056A (ja) * 2007-04-24 2008-11-06 National Institute For Materials Science 走査型透過電子顕微鏡
JP2012104426A (ja) * 2010-11-12 2012-05-31 Hitachi High-Technologies Corp 荷電粒子光学装置及びレンズ収差測定方法

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JPH11250847A (ja) * 1998-02-27 1999-09-17 Hitachi Ltd 収束荷電粒子線装置およびそれを用いた検査方法
JP2006173027A (ja) * 2004-12-20 2006-06-29 Hitachi High-Technologies Corp 走査透過電子顕微鏡、及び収差測定方法、ならびに収差補正方法
JP6163063B2 (ja) * 2013-09-13 2017-07-12 株式会社日立ハイテクノロジーズ 走査透過電子顕微鏡及びその収差測定方法
JP6818588B2 (ja) * 2017-02-24 2021-01-20 株式会社ホロン サンプル傾斜自動補正装置およびサンプル傾斜自動補正方法
JP6857575B2 (ja) * 2017-08-24 2021-04-14 日本電子株式会社 収差測定方法および電子顕微鏡

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Publication number Priority date Publication date Assignee Title
US6552340B1 (en) * 2000-10-12 2003-04-22 Nion Co. Autoadjusting charged-particle probe-forming apparatus
JP2008270056A (ja) * 2007-04-24 2008-11-06 National Institute For Materials Science 走査型透過電子顕微鏡
JP2012104426A (ja) * 2010-11-12 2012-05-31 Hitachi High-Technologies Corp 荷電粒子光学装置及びレンズ収差測定方法

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