WO2019180903A1 - Scanning electron microscope and imaging method thereof - Google Patents

Scanning electron microscope and imaging method thereof Download PDF

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Publication number
WO2019180903A1
WO2019180903A1 PCT/JP2018/011622 JP2018011622W WO2019180903A1 WO 2019180903 A1 WO2019180903 A1 WO 2019180903A1 JP 2018011622 W JP2018011622 W JP 2018011622W WO 2019180903 A1 WO2019180903 A1 WO 2019180903A1
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sample
scanning
image
electron beam
electron microscope
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PCT/JP2018/011622
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French (fr)
Japanese (ja)
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修平 藪
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株式会社 日立ハイテクノロジーズ
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Priority to PCT/JP2018/011622 priority Critical patent/WO2019180903A1/en
Priority to JP2020507235A priority patent/JP6920539B2/en
Publication of WO2019180903A1 publication Critical patent/WO2019180903A1/en

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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

Definitions

  • the present invention utilizes amplification of secondary electrons by residual molecules around the sample, and the electrons or ions amplified thereby, or the light generated during amplification. It belongs to the method of forming an image by detecting.
  • the present invention relates to a technique for improving the image quality of a secondary electron image in high-speed scanning obtained by SEM.
  • an Everhard-Thornley detector (ET detector) is used to detect secondary electrons with a scanning electron microscope.
  • secondary electrons generated on the surface of the sample are accelerated at a high voltage of about 10 kV, and converted into light by a scintillator to be detected.
  • Such an Everhard-Thornley detector uses a high voltage of about 10 kV. Therefore, if the degree of vacuum in the sample chamber is not more than 10 ⁇ 1 Pa, discharge due to the high voltage occurs and cannot be used.
  • Patent Document 1 discloses a technique for obtaining a secondary electron image by detecting an ionic current generated by a gas amplification action between secondary electrons and residual gas molecules.
  • Patent Document 2 discloses a technique for obtaining a secondary electron image by detecting light generated by collision between secondary electrons and residual gas molecules.
  • the response speed of the SEM detector affects the image quality during high-speed scanning.
  • an electron beam is scanned over a sample, and the magnitude of the signal amount of signal electrons such as secondary electrons generated at that time is displayed on an image and displayed.
  • the scanning speed of the electron beam can be changed according to the purpose of observation.
  • a high-speed scan is used. For example, in a TV scan, an electron beam is scanned at a speed of about 80 nanoseconds / pixel. At this time, if the response speed of the detector is slower than the scanning time per pixel, an image flow occurs and the detailed structure on the sample cannot be confirmed.
  • the response speed in a detector using such a gas amplification phenomenon is mainly determined by two factors.
  • gas amplification in addition to the amplification phenomenon of electrons and ions, multiple phenomena such as recombination of electrons and ions occur simultaneously. Therefore, it is known that it takes some time for the number of electrons and ions around the sample to settle down to a steady state.
  • Another factor that determines the response speed is the response speed depending on the frequency band of the amplifier circuit.
  • the amplification factor is increased in order to amplify the signal by an electronic circuit and generally not be affected by disturbance.
  • the frequency band becomes smaller ( ⁇ 100 kHz), so the response speed becomes worse.
  • a detector that detects light generated as a result of gas amplification can amplify a signal using an amplifier such as a photomultiplier tube that has a fast response speed ( ⁇ 100 nanoseconds). It is important to improve.
  • the response speed of the gas amplification action is improved.
  • an image flow caused by the gas amplification similarly occurs.
  • the Everhard-Thornley detector used in high vacuum of 10 ⁇ 1 Pa or less does not use the gas amplification action, and thus such image flow does not occur.
  • the response speed of the detector is important for increasing the throughput of observation and facilitating the search for the field of view.
  • the irradiation optical system for irradiating the sample with the electron beam the sample stage, the electric field supply electrode for supplying the electric field acting on the electrons generated by the irradiation of the electron beam, and the scanning speed of the electron beam.
  • a deflection coil to be controlled and a power source for applying a voltage to the sample, and a voltage closer to the ground than the voltage applied to the sample when the electron beam scanning speed is fast is applied to the sample when the electron beam scanning speed is slow.
  • the response speed of the detector is higher than that of a conventional detection system. Can be realized.
  • FIG.2 (b) for demonstrating the image flow of a scanning electron microscopic image. It is an image which shows an example of the scanning electron microscopic image in this invention. It is a scanning electron microscope image which shows the suppression effect of the image flow of this invention. It is a figure which shows the scanning electron microscope image of the sample which vapor-deposited platinum (Pt) on the silicon
  • FIG. 8A is a schematic diagram of FIG. 7A for explaining an example of an image flow of a scanning electron microscope image. It is a scanning electron microscope image at the time of applying a positive voltage to the sample in this invention. It is a scanning electron microscope image at the time of applying a negative voltage to the sample in this invention.
  • FIG. 8C is a schematic diagram of FIG. 7C and FIG. 7D for explaining an effect of suppressing image flow of an image of a scanning electron microscope. It is a figure which shows the example of the graphic user interface (GUI) in this invention.
  • GUI graphic user interface
  • FIG. 1 is a diagram showing a first embodiment of a scanning electron microscope according to the present invention.
  • the scanning electron microscope system 100 includes a filament 101, a Wehnelt 102, an anode 103, a primary electron beam 104, an upper gun alignment coil 105, a lower gun alignment coil 106, a first focusing lens 107, a second focusing lens 108, an objective aperture 109, an aligner.
  • a high voltage control circuit 119 applies a desired voltage to the filament 101, Wehnelt 102, and anode 103, and the primary electron beam 104 is emitted from the filament 101.
  • the emitted primary electron beam 104 is focused by the first focusing lens 107 and the second focusing lens 108 and then focused on the sample 114 by the objective lens 113. Further, the primary electron beam 104 focused on the sample 114 is simultaneously scanned on the sample 104 by the upper deflection coil 111 and the lower deflection coil 112. Secondary electrons are generated from the sample 114 with the irradiation of the primary electron beam 104.
  • the secondary electrons are accelerated in the direction of the electric field supply electrode 132 by the electric field generated by the electric field supply electrode 132 to which a positive voltage (typically about 1 to 600 V) is applied.
  • the accelerated secondary electrons collide with gas molecules around the sample to generate electron-ion pairs.
  • the electrons generated by the collision with the secondary electrons and the gas molecules are directed toward the electric field supply electrode 132 while repeating the collision with the gas molecules.
  • This process causes avalanche (gas amplification), and the number of electrons and ions increases exponentially as the electric field supply electrode 132 is approached.
  • light generated at the time of collision of gas molecules with electrons is detected by the detector 117 as a signal 116 having secondary electron information, and is amplified by the amplifier 118.
  • a photomultiplier tube may be used as the detector 117 or the amplifier 118, or a photodiode may be used as the detector 117 and an amplifier circuit may be used as the amplifier 118.
  • light is used as the signal 116 having secondary electron information.
  • the electron flow or ion flow generated as a result of gas amplification may be detected by the detector 117 as the signal 116.
  • the upper deflection coil 111 and the lower deflection coil 112 are controlled by a deflection control circuit 124, and the scanning speed of the primary electron beam 104 can be changed according to the purpose of observation. For example, when it is desired to obtain an image with a good S / N, the scanning speed of the primary electron beam 104 is decreased.
  • the scanning electron microscope a square or rectangular area on the sample 114 is scanned with the primary electron beam 104, and the position where the sample 114 is scanned is synchronized with the position where the display device 129 displays the intensity of the signal electrons. I got a statue at.
  • the scanning speed of the primary electron beam 104 is low, the amount of the primary electron beam 104 irradiated on the sample 114 also increases, so that the number of signals 116 that can be acquired increases and an image with a good S / N can be obtained.
  • the sample 114 is scanned with the primary electron beam 104 at 10 to several hundred seconds per frame.
  • the scanning speed of the primary electron beam 104 is increased. This is because the display device 129 displays the sample table 115 with good followability with respect to the movement of the sample stage 115 and the focus adjustment. In such a case, a scan of about several tens of milliseconds to one second per frame is generally used.
  • the response speed of the detector 117 or the amplifier 118 is slower than the scanning speed, crosstalk of the signal 116 occurs in the adjacent display pixels, causing image flow on the display image, and the sample 114. Concavity and convexity information and composition information resulting from the generated secondary electrons and reflected electrons are lost.
  • the scanning time of the primary electron beam 104 per pixel is about 130 nanoseconds. Therefore, in order to display information without losing information during such a high-speed scan, the response time of the detector 117 needs to be faster than the scan time of the primary electron beam 104 per pixel, and the amplifier 118 has an amplifier circuit. Therefore, a frequency band of 1/130 nanosecond, that is, 7.7 MHz or higher is required.
  • the response due to the gas amplification action is the main response speed of the detector. Since the response time due to gas amplification is usually several tens of microseconds to several tens of milliseconds, it is necessary to obtain the SEM image with no image flow at a low scanning speed.
  • FIG. 2A is a figure explaining an example of the observation sample in this invention.
  • the sample 114 includes a copper mesh 201 and a copper ring 202.
  • FIG. 2B is a scanning electron microscope image showing an example of an image flow in the present invention, and shows an example of an image of a scanning electron microscope acquired by detecting light generated as a result of gas amplification.
  • images of the copper mesh 201 and the copper ring 202 are acquired at a scanning speed of the primary electron beam 104 of about 95 nanoseconds / pixel. At this time, scanning is about 80 milliseconds per frame, and FIG.
  • FIG. 2B shows an example in which an image is acquired at a relatively high scanning speed.
  • the degree of vacuum around the sample 114 is about 50 Pa, and the vicinity of the boundary between the copper mesh 201 and the copper ring 202 is observed.
  • the primary electron beam 104 is scanning from the left to the right of the image.
  • FIG. 2C is a schematic diagram of FIG. 2B for explaining the image flow of the scanning electron microscopic image.
  • FIG. 2 (d) is an image showing an example of a scanning electron microscopic image in the present invention.
  • FIG. 2 (d) shows the same field of view as FIG. 2 (b) under the condition that the scanning speed of the primary electron beam 104 is about 3400 nanoseconds / pixel and about 4 seconds per frame as an example observed with a relatively slow scan.
  • the image flow portion 203 shown in FIG. 2 (c) is generated in the copper ring portion in FIG. 2 (b) observed at the high primary electron beam 104 scanning speed.
  • the scanning line of the mesh void 204 is darker than the original copper ring 202 as the image flow portion 203, and the darkness of the image flow becomes closer to the right side of the figure. It shows that is thin. This is because, since the response speed of the detector is delayed with respect to the scanning speed of the primary electron beam 104, the gap portion 204 between the copper meshes 201 flows from the left side to the right side of the image in the scanning direction. This is because the part 203 is displayed.
  • FIG. 2D since the scanning speed of the primary electron beam 104 is relatively slow and the difference from the response speed of the detector is small, the image flow is reduced as compared with FIG. Then, there is almost no image flow.
  • FIG. 2 (e) is a scanning electron microscope image showing the effect of suppressing the image flow of the present invention.
  • the voltage applied to the sample stage 115 and the sample 114 can be adjusted using the power supply 127 for the sample stage.
  • FIG. 2 (e) shows that the scanning speed of 104 of the same primary electron beam as in FIG. 2 (b) is about 95 nanoseconds when a voltage of ⁇ 20V is applied to the sample 114 using the power supply 127 for the sample stage. It is the scanning electron microscope image which acquired the image by / pixel.
  • the image flow part 203 seen in FIG. 2 (b) and illustrated using FIG. 2 (c) is almost not seen, and the scanning speed of the primary electron beam 104 is high. However, the image flow is suppressed.
  • FIG. 3A is a view showing a scanning electron microscopic image of a sample in which platinum (Pt) is vapor-deposited on a silicon (Si) substrate.
  • a sample in which platinum (Pt) was vapor-deposited on a silicon (Si) substrate was prepared, and an image for observing the boundary surface between silicon and platinum was acquired.
  • the image is acquired under the condition that the scanning speed of the primary electron beam 104 is about 95 nanoseconds / pixel and about 160 milliseconds per frame.
  • FIG. 3B is a diagram showing a line profile obtained by scanning the portion of the line profile acquisition unit 301 in FIG. 3A from the left side to the right side of the image with the primary electron beam 104. Since the silicon and platinum parts are almost uniform and almost constant image signal intensity can be obtained in each region, the response time of gas amplification can be obtained by obtaining the line profile of the image at those boundaries. It is a figure which shows the result of having evaluated quantitatively.
  • FIG. 4A is a diagram showing a response time curve of the detector when a negative voltage is applied to the sample
  • FIG. 4B is a response time curve of the detector when a positive voltage is applied to the sample.
  • FIG. The graph shows the result of acquiring a line profile near the boundary surface between silicon and platinum by changing the voltage applied to the sample 114 in steps of 1V from -5V to + 5V.
  • the degree of vacuum around the sample 114 is 50 Pa
  • the acceleration voltage of the primary electron beam 104 is 15 kV
  • the working distance is 10 mm.
  • FIG. 5 is a diagram showing the relationship between the voltage applied to the sample and the response time of the detector, and shows the result of obtaining the 100-10% response time from the line profile of FIG.
  • the response time is 31 microseconds, but by applying a voltage of + 5V to the sample 114, the response time is 16 microseconds.
  • Response time improved to 13 microseconds by applying a voltage of -5V.
  • the measurement range is limited by the width of the image to be acquired, and when the applied voltage is low, it can not be acquired until the signal intensity reaches a steady state, so the actual response time is improved this time It is thought that it is larger than the result.
  • FIG. 6A is a scanning electron microscope image showing an example of the image flow of an image when the insulating sample in the present invention is observed.
  • no voltage is applied to the paper as the insulating sample, that is, to the sample.
  • a scanning electron microscopic image with an applied voltage of 0 V is shown. Overexposure and image flow are caused by charging of the sample surface, and the structure of paper fibers cannot be observed.
  • FIG. 6A is a scanning electron microscope image showing an example of the image flow of an image when the insulating sample in the present invention is observed. In the case where no voltage is applied to the paper as the insulating sample, that is, to the sample. A scanning electron microscopic image with an applied voltage of 0 V is shown. Overexposure and image flow are caused by charging of the sample surface, and the structure of paper fibers cannot be observed.
  • FIG. 6B is a scanning electron microscope image showing suppression of image flow of an image when a positive voltage is applied to the insulating sample in the present invention and observed, and a voltage of +10 V is applied to the paper as the insulating sample.
  • a scanning electron microscope image is shown.
  • FIG. 6C is a scanning electron microscope image showing suppression of image flow of an image when a negative voltage is applied to the insulating sample in the present invention and observed, and a voltage of ⁇ 10 V is applied to the paper as the insulating sample.
  • the scanning electron microscope image in the case is shown. Both the scanning electron microscopic images of FIG. 6B and FIG. 6C can suppress charging of the sample surface and image flow, and the structure of the fiber of the paper that is the insulating sample can be clearly confirmed. .
  • the image flow suppression effect in the detector using the ion current detection type gas amplification phenomenon will be described.
  • an example of the effect of suppressing image flow by applying a voltage to a sample in a detector that detects ions obtained as a result of gas amplification is shown.
  • the sample 114 the observation with a scanning electron microscope is performed using the copper mesh 201 and the copper ring 202 similarly to FIGS. 2 (a) to 2 (e).
  • the degree of vacuum around the sample 114 is 50 Pa, and the scanning speed is 1.56 microseconds / pixel.
  • FIG. 7A is a scanning electron microscope showing an example of the image flow of the image in the present invention, and is a scanning electron microscope image obtained by observing the copper mesh 201 and the copper ring 202 when the applied voltage to the sample is 0V. is there.
  • FIG. 7B is a schematic diagram of FIG. 7A for explaining an example of the image flow of the image of the scanning electron microscope.
  • the image flow portion 203 shown in FIG. 7B is seen in the copper ring 202 portion for the reason described above.
  • 7A also scans the primary electron beam 104 from the left to the right of the scanning electron microscope image, and the response speed of the detector is delayed with respect to the primary electron beam 104 scanning speed. This is because the gap portion 204 between the two flows from the left side to the right side of the image in the scanning direction and the image flow portion 203 is displayed.
  • FIG. 7C is a scanning electron microscope image when a positive voltage is applied to the sample in the present invention, and the scanning speed under the same conditions as the image acquisition in FIG. 7A is 1.56 microseconds / pixel. It is a scanning electron microscope image at the time of applying a + 10V positive voltage to a sample.
  • FIG. 7D is a scanning electron microscope image when a negative voltage is applied to the sample in the present invention, and the scanning speed under the same conditions as the image acquisition in FIG. 7A is 1.56 microseconds / second. It is a scanning electron microscope image when a negative voltage of ⁇ 10 V is applied to a sample in a pixel.
  • FIG. 7E is a schematic diagram of FIG. 7C and FIG.
  • Example 1 the effect of suppressing image flow by applying a voltage to the sample 114 was described.
  • a voltage is applied to the sample 114 to suppress image flow
  • the SEM image may become dark and the S / N of the image may deteriorate.
  • the image flow can be suppressed by applying a voltage to the sample 114, it is considered that the time during which the gas amplification acts is shortened and the signal due to the gas amplification is also reduced.
  • the user uses the scanning electron microscope while changing the type of scanning according to the case of searching the visual field, adjusting the focus, or saving the image.
  • the scanning speed of the primary electron beam 104 can be changed by a button displayed on a graphical user interface (GUI), a mechanical button switch, or the like.
  • GUI graphical user interface
  • FIG. 8 is a diagram showing an example of a graphic user interface (GUI) in the present invention.
  • GUI graphic user interface
  • a high-speed scan button 801 used for visual field search
  • a low-speed scan button 802 used for image confirmation and fine adjustment of focus
  • a field-restricted scan button 803 used for focus adjustment
  • an image display unit 804 a focus adjustment slider 805 for adjusting the focus of the primary electron beam 104
  • an astigmatism adjustment slider 806 for adjusting the astigmatism of the primary electron beam 104, and the like, are provided so that the user can scan various primary electron beam 104 scanning conditions.
  • the image acquired by the scanning electron microscope can be displayed while switching between.
  • image flow occurs during observation because the scanning time of the primary electron beam 104 per pixel is shorter than the response speed of the gas amplification phenomenon. In this case, image flow does not occur in a slow scan in which the scan time of the primary electron beam 104 per pixel is longer than the response speed of the gas amplification phenomenon. That is, it is only necessary that the image flow can be suppressed only during high speed scanning.
  • a voltage is applied to the sample 114, the signal due to gas amplification becomes small, and the S / N of the image may deteriorate.
  • the S / N is not impaired at the time of low-speed scanning, and the image flow is at the time of high-speed scanning. Can be suppressed.
  • the voltage applied to the sample 114 may be changed according to the scanning speed of the primary electron beam 104.
  • image flow can be suppressed.
  • the voltage applied to the sample 114 is changed, the state of the gas amplification phenomenon changes and the luminance of the image also changes. Therefore, the voltage of the electric field supply electrode 132 is scanned with the primary electron beam 104 to compensate for the luminance change.
  • the process of changing the speed according to the speed or automatically adjusting the brightness of the image may be executed simultaneously with the change of the scanning speed of the primary electron beam 104. In addition, it is considered effective to control the amplification degree of the amplifier 118 to be changed.

Abstract

The purpose of the present invention is to provide a technology that enables a detector using gas amplification to have improved response speed. The scanning electron microscope according to the present invention is provided with: an irradiation optical system for irradiating a specimen with an electron beam; a specimen stage; an electric field supply electrode for supplying an electric field that acts on electrons generated by irradiation with an electron beam; a deflection coil for controlling the scanning speed of the electron beam; and a power supply for applying a voltage to the specimen, wherein the abovementioned problem of the present invention is solved by applying to a specimen a voltage that is closer to the ground voltage when the scanning speed of the electron beam is slow, as compared with the voltage applied to the specimen when the electron beam scanning speed is fast.

Description

[規則37.2に基づきISAが決定した発明の名称]　走査電子顕微鏡及びその撮像方法[Name of invention determined by ISA based on Rule 37.2] Scanning electron microscope and imaging method thereof
　本発明は走査電子顕微鏡（以下、ＳＥＭ）による二次電子観察手法のうち、試料周辺の残留分子による二次電子の増幅を利用し、それによって増幅される電子もしくはイオン、あるいは増幅時に発生する光を検出することで画像を形成する方法に属する。本発明はＳＥＭによって得られる高速走査における二次電子像の像質向上を実現するための技術に関するものである。 Of the secondary electron observation techniques using a scanning electron microscope (hereinafter referred to as SEM), the present invention utilizes amplification of secondary electrons by residual molecules around the sample, and the electrons or ions amplified thereby, or the light generated during amplification. It belongs to the method of forming an image by detecting. The present invention relates to a technique for improving the image quality of a secondary electron image in high-speed scanning obtained by SEM.
　通常、走査電子顕微鏡で二次電子を検出するには、Ｅｖｅｒｈａｒｄ－Ｔｈｏｒｎｌｅｙ検出器（Ｅ－Ｔ検出器）が用いられる。これは、試料表面で発生した二次電子を約１０ｋＶの高電圧で加速させ、シンチレータにおいて光に変換して検出するものである。このようなＥｖｅｒｈａｒｄ－Ｔｈｏｒｎｌｅｙ検出器は、約１０ｋＶという高電圧を用いるため、試料室内部の真空度が１０－１Ｐａ以下でないと、高電圧に起因する放電が生じ使用することができない。 Usually, an Everhard-Thornley detector (ET detector) is used to detect secondary electrons with a scanning electron microscope. In this method, secondary electrons generated on the surface of the sample are accelerated at a high voltage of about 10 kV, and converted into light by a scintillator to be detected. Such an Everhard-Thornley detector uses a high voltage of about 10 kV. Therefore, if the degree of vacuum in the sample chamber is not more than 10 −1 Pa, discharge due to the high voltage occurs and cannot be used.
　一方、試料室内部を数Ｐａ～数１０００Ｐａ程度の圧力にして、二次電子を観察する手法があり、これは試料表面での帯電を低減させる場合や、高真空では蒸発してしまう液体を試料に含有した状態で観察する場合に用いられる。この場合、二次電子を観察する手法として、試料周辺の残留気体分子を利用して二次電子を増幅させる手法が良く知られている。 On the other hand, there is a method for observing secondary electrons by setting the pressure inside the sample chamber to several Pa to several thousand Pa, and this is used to reduce the charge on the sample surface or to remove liquid that evaporates in a high vacuum. It is used when observing in the state of being contained. In this case, as a technique for observing secondary electrons, a technique for amplifying secondary electrons using residual gas molecules around the sample is well known.
　特許文献１には、二次電子と残留気体分子とのガス増幅作用によって発生するイオン電流を検出して二次電子像を得る手法が開示されている。 Patent Document 1 discloses a technique for obtaining a secondary electron image by detecting an ionic current generated by a gas amplification action between secondary electrons and residual gas molecules.
　特許文献２には、二次電子と残留気体分子との衝突によって発生する光を検出して二次電子像を得る手法が開示されている。 Patent Document 2 discloses a technique for obtaining a secondary electron image by detecting light generated by collision between secondary electrons and residual gas molecules.
特開２００６－２２８５８６号公報JP 2006-228586 A 米国特許ＵＳ４９９２６６２号明細書US Patent US4992662
　ＳＥＭの検出器の応答速度は、高速スキャン時における像質に影響する。ＳＥＭでは電子線を試料上で走査させ、そのときに発生する二次電子などの信号電子の信号量の大きさを画像に出して表示させている。電子線を走査する速度は観察の目的に応じて変えられるようになっている。視野探しや帯電を軽減させる場合は高速のスキャンが用いられ、例えば、ＴＶスキャンでは約８０ナノ秒／ピクセルの速さで電子線を走査している。このとき、検出器の応答速度が１ピクセルあたりの走査時間よりも遅い場合、像流れが生じ、試料上の詳細な構造を確認することができない。 The response speed of the SEM detector affects the image quality during high-speed scanning. In the SEM, an electron beam is scanned over a sample, and the magnitude of the signal amount of signal electrons such as secondary electrons generated at that time is displayed on an image and displayed. The scanning speed of the electron beam can be changed according to the purpose of observation. In order to reduce the field of view and charge, a high-speed scan is used. For example, in a TV scan, an electron beam is scanned at a speed of about 80 nanoseconds / pixel. At this time, if the response speed of the detector is slower than the scanning time per pixel, an image flow occurs and the detailed structure on the sample cannot be confirmed.
　ガス増幅を利用する二次電子検出器では、二次電子と試料周辺の残留分子による相互作用により電子を指数関数的に増幅させている。このようなガス増幅現象を利用する検出器における応答速度は主に２つの要素によって決定される。１つは、ガス増幅現象がもたらす応答速度の悪化である。ガス増幅では電子およびイオンの増幅現象のほか、電子やイオンの再結合など同時に複数の現象が起こっている。そのため、試料周辺での電子やイオン数が定常状態に落ち着くまである程度時間がかかることが知られている。もう１つの応答速度を決定する要因は、増幅回路の周波数帯域による応答速度である。ガス増幅により信号を増幅されたとしても信号量は微小なため、ＳＥＭ像にするために増幅する必要がある。イオンや電子を検出する場合は電子回路によって信号を増幅させ、一般的に外乱の影響を受けないようにするために、その増幅率を大きくしている。しかし、増幅率を大きくすると周波数帯域が小さくなる（＜１００キロＨｚ）ため応答速度が悪くなる。一方、ガス増幅の結果発生する光を検出する検出器においては光電子増倍管等の応答速度の速い（＜１００ナノ秒）増幅器を用いて信号を増幅できるため、この場合はガス増幅による応答速度を向上させることが重要となる。 In the secondary electron detector using gas amplification, electrons are exponentially amplified by the interaction between secondary electrons and residual molecules around the sample. The response speed in a detector using such a gas amplification phenomenon is mainly determined by two factors. One is the deterioration in response speed caused by the gas amplification phenomenon. In gas amplification, in addition to the amplification phenomenon of electrons and ions, multiple phenomena such as recombination of electrons and ions occur simultaneously. Therefore, it is known that it takes some time for the number of electrons and ions around the sample to settle down to a steady state. Another factor that determines the response speed is the response speed depending on the frequency band of the amplifier circuit. Even if the signal is amplified by gas amplification, the amount of signal is very small, so it is necessary to amplify it to obtain an SEM image. When detecting ions and electrons, the amplification factor is increased in order to amplify the signal by an electronic circuit and generally not be affected by disturbance. However, if the amplification factor is increased, the frequency band becomes smaller (<100 kHz), so the response speed becomes worse. On the other hand, a detector that detects light generated as a result of gas amplification can amplify a signal using an amplifier such as a photomultiplier tube that has a fast response speed (<100 nanoseconds). It is important to improve.
　電界供給電極付近にイオン検出電極を設けることで、ガス増幅作用の応答速度の向上を図っているが、高速スキャンでは同様にガス増幅に起因する像流れが生じる。一方、１０－１Ｐａ以下の高真空化で用いられるＥｖｅｒｈａｒｄ－Ｔｈｏｒｎｌｅｙ検出器では、ガス増幅作用を用いないため、このような像流れは生じない。検出器の応答速度は前述したように、観察の高スループット化や視野探しの容易性などに重要であるが、ガス増幅を利用した検出器において十分な応答速度を得られている手法はない。そのため、ガス増幅作用を利用した検出器において、応答速度の向上は急務の課題である。 By providing an ion detection electrode in the vicinity of the electric field supply electrode, the response speed of the gas amplification action is improved. However, in the high-speed scan, an image flow caused by the gas amplification similarly occurs. On the other hand, the Everhard-Thornley detector used in high vacuum of 10 −1 Pa or less does not use the gas amplification action, and thus such image flow does not occur. As described above, the response speed of the detector is important for increasing the throughput of observation and facilitating the search for the field of view. However, there is no method that can obtain a sufficient response speed in a detector using gas amplification. Therefore, in the detector using the gas amplification action, improvement of the response speed is an urgent issue.
　本発明の走査電子顕微鏡では、電子ビームを試料に照射する照射光学系と、試料台と、電子ビームの照射により発生する電子に作用する電界を供給する電界供給電極と、電子ビームの走査速度を制御する偏向コイルと、試料に電圧を印加する電源と、を備え、電子ビームの走査速度が速い時に試料に印加した電圧よりグラウンドに近い電圧を電子ビームの走査速度が遅い時に試料に印加することで、上述の課題を解決する。 In the scanning electron microscope of the present invention, the irradiation optical system for irradiating the sample with the electron beam, the sample stage, the electric field supply electrode for supplying the electric field acting on the electrons generated by the irradiation of the electron beam, and the scanning speed of the electron beam. A deflection coil to be controlled and a power source for applying a voltage to the sample, and a voltage closer to the ground than the voltage applied to the sample when the electron beam scanning speed is fast is applied to the sample when the electron beam scanning speed is slow. Thus, the above-mentioned problem is solved.
　本発明により、試料周辺の残留ガス分子と二次電子とのガス増幅作用を用いて二次電子情報を含んだ画像を形成するＳＥＭにおいて、従来の検出系に比べて検出器の応答速度の高速化を実現できる。 According to the present invention, in an SEM that forms an image including secondary electron information using the gas amplification action of residual gas molecules and secondary electrons around the sample, the response speed of the detector is higher than that of a conventional detection system. Can be realized.
本発明に基づく走査電子顕微鏡の第１の実施例を示す図である。It is a figure which shows the 1st Example of the scanning electron microscope based on this invention. 本発明における観察試料の一例を説明する図である。It is a figure explaining an example of the observation sample in this invention. 本発明における画像の像流れの一例を示す走査電子顕微鏡像である。It is a scanning electron microscope image which shows an example of the image flow of the image in this invention. 走査電子顕微像の像流れを説明するための図２（ｂ）の模式図である。It is a schematic diagram of FIG.2 (b) for demonstrating the image flow of a scanning electron microscopic image. 本発明における走査電子顕微像の一例を示す画像である。It is an image which shows an example of the scanning electron microscopic image in this invention. 本発明の像流れの抑制効果を示す走査電子顕微鏡像である。It is a scanning electron microscope image which shows the suppression effect of the image flow of this invention. シリコン（Ｓｉ）基板上に、白金（Ｐｔ）を蒸着した試料の走査電子顕微像を示す図である。It is a figure which shows the scanning electron microscope image of the sample which vapor-deposited platinum (Pt) on the silicon | silicone (Si) board | substrate. 走査電子顕微鏡の画像より取得したラインプロファイルを示す図である。It is a figure which shows the line profile acquired from the image of the scanning electron microscope. 試料に負電圧を印加した場合の検出器の応答時間曲線を示す図である。It is a figure which shows the response time curve of the detector at the time of applying a negative voltage to a sample. 試料に正電圧を印加した場合の検出器の応答時間曲線を示す図である。It is a figure which shows the response time curve of the detector at the time of applying a positive voltage to a sample. 試料に印加する電圧と検出器の応答時間の関係を示す図である。It is a figure which shows the relationship between the voltage applied to a sample, and the response time of a detector. 本発明における絶縁試料を観察した際の画像の像流れの一例を示す走査電子顕微鏡像である。It is a scanning electron microscope image which shows an example of the image flow of the image at the time of observing the insulation sample in this invention. 本発明における絶縁試料に正電圧を印加し観察した際の画像の像流れの抑制を示す走査電子顕微鏡像である。It is a scanning electron microscope image which shows suppression of the image flow of the image at the time of applying and applying a positive voltage to the insulation sample in this invention. 本発明における絶縁試料に負電圧を印加し観察した際の画像の像流れの抑制を示す走査電子顕微鏡像である。It is a scanning electron microscope image which shows suppression of the image flow of the image at the time of applying and applying a negative voltage to the insulation sample in this invention. 本発明における画像の像流れの一例を示す走査電子顕微鏡である。It is a scanning electron microscope which shows an example of the image flow of the image in this invention. 走査電子顕微鏡の画像の像流れの一例を説明するための図７（ａ）の模式図である。FIG. 8A is a schematic diagram of FIG. 7A for explaining an example of an image flow of a scanning electron microscope image. 本発明における試料に正電圧を印加した場合の走査電子顕微鏡像である。It is a scanning electron microscope image at the time of applying a positive voltage to the sample in this invention. 本発明における試料に負電圧を印加した場合の走査電子顕微鏡像である。It is a scanning electron microscope image at the time of applying a negative voltage to the sample in this invention. 走査電子顕微鏡の画像の像流れの抑制効果を説明するための図７（ｃ）および図７（ｄ）の模式図である。FIG. 8C is a schematic diagram of FIG. 7C and FIG. 7D for explaining an effect of suppressing image flow of an image of a scanning electron microscope. 本発明におけるグラフィックユーザーインターフェース（ＧＵＩ）の例を示す図である。It is a figure which shows the example of the graphic user interface (GUI) in this invention.
　以下の実施の形態において、便宜上その必要があるときは、複数のセクションまたは実施の形態に分割して説明するが、特に明示した場合を除き、それらはお互いに無関係なものではなく、一方は他方の一部または全部の変形例、詳細、補足説明等の関係にある。 In the following embodiments, when necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other, and one is the other. There are some or all of the modifications, details, supplementary explanations, and the like.
　また、以下の実施の形態で用いる図面においては、平面図であっても図面を見易くするためにハッチングを付す場合もある。また、以下の実施の形態を説明するための全図において、同一機能を有するものは原則として同一の符号を付し、その繰り返しの説明は省略する。以下、本発明の実施の形態を図面に基づいて詳細に説明する。 Also, in the drawings used in the following embodiments, hatching may be added to make the drawings easy to see even if they are plan views. In all the drawings for explaining the following embodiments, components having the same function are denoted by the same reference numerals in principle, and repeated description thereof is omitted. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
　図１は、本発明に基づく走査電子顕微鏡の第１の実施例を示す図である。走査電子顕微鏡システム１００は、フィラメント１０１、ウェネルト１０２、陽極１０３、一次電子ビーム１０４、上段ガンアライメントコイル１０５、下段ガンアライメントコイル１０６、第一集束レンズ１０７、第二集束レンズ１０８、対物絞り１０９、アライナー１１０、上段偏向コイル１１１、下段偏向コイル１１２、対物レンズ１１３、試料１１４、試料台１１５、信号１１６、検出器１１７、増幅器１１８、高電圧制御回路１１９、ガンアライメント制御回路１２０、第一集束レンズ制御回路１２１、第二集束レンズ制御回路１２２、アライナー制御回路１２３、偏向制御回路１２４、対物レンズ制御回路１２５、電界供給電極用電源１２６、試料台用電源１２７、コンピュータ１２８、表示装置１２９、記憶手段１３０、入力手段１３１、および電界供給電極１３２を有する。 FIG. 1 is a diagram showing a first embodiment of a scanning electron microscope according to the present invention. The scanning electron microscope system 100 includes a filament 101, a Wehnelt 102, an anode 103, a primary electron beam 104, an upper gun alignment coil 105, a lower gun alignment coil 106, a first focusing lens 107, a second focusing lens 108, an objective aperture 109, an aligner. 110, upper deflection coil 111, lower deflection coil 112, objective lens 113, sample 114, sample stage 115, signal 116, detector 117, amplifier 118, high voltage control circuit 119, gun alignment control circuit 120, first focusing lens control Circuit 121, second focusing lens control circuit 122, aligner control circuit 123, deflection control circuit 124, objective lens control circuit 125, electric field supply electrode power supply 126, sample stage power supply 127, computer 128, display device 129, storage means 130 ,input Having steps 131 and electric field supply electrode 132,.
　走査電子顕微鏡は、高電圧制御回路１１９によってフィラメント１０１、ウェネルト１０２、陽極１０３に所望の電圧が印加され、フィラメント１０１より一次電子ビーム１０４が放出される。放出された一次電子ビーム１０４は第一集束レンズ１０７、第二集束レンズ１０８で集束された後、対物レンズ１１３によって試料１１４に集束される。また、試料１１４上に集束される一次電子ビーム１０４は同時に、上段偏向コイル１１１および下段偏向コイル１１２によって試料１０４上を走査される。一次電子ビーム１０４の照射に伴って試料１１４からは二次電子が発生する。二次電子は正電圧（典型的には１～６００Ｖ程度）を印加した電界供給電極１３２の作る電界によって当該電界供給電極１３２方向に加速される。加速された二次電子は試料周辺のガス分子と衝突し電子－イオン対が生成される。二次電子およびガス分子との衝突により発生する電子は、ガス分子との衝突を繰り返しながら電界供給電極１３２方向に向かう。 In the scanning electron microscope, a high voltage control circuit 119 applies a desired voltage to the filament 101, Wehnelt 102, and anode 103, and the primary electron beam 104 is emitted from the filament 101. The emitted primary electron beam 104 is focused by the first focusing lens 107 and the second focusing lens 108 and then focused on the sample 114 by the objective lens 113. Further, the primary electron beam 104 focused on the sample 114 is simultaneously scanned on the sample 104 by the upper deflection coil 111 and the lower deflection coil 112. Secondary electrons are generated from the sample 114 with the irradiation of the primary electron beam 104. The secondary electrons are accelerated in the direction of the electric field supply electrode 132 by the electric field generated by the electric field supply electrode 132 to which a positive voltage (typically about 1 to 600 V) is applied. The accelerated secondary electrons collide with gas molecules around the sample to generate electron-ion pairs. The electrons generated by the collision with the secondary electrons and the gas molecules are directed toward the electric field supply electrode 132 while repeating the collision with the gas molecules.
　この過程により電子なだれ（ガス増幅）が生じ、電子数、イオン数は、電界供給電極１３２に近づくに従って指数関数的に増大する。また、電子とのガス分子の衝突時に発生する光は、二次電子情報を持つ信号１１６として検出器１１７によって検出され、増幅器１１８によって増幅される。検出器１１７や増幅器１１８として例えば、光電子増倍管を用いることができるし、あるいは検出器１１７としてフォトダイオードを用いて増幅器１１８として増幅回路を用いても良い。実施例１では、二次電子情報を持つ信号１１６として光を用いるが、ガス増幅の結果発生する電子流やイオン流を信号１１６として検出器１１７によって検出してもよい。 This process causes avalanche (gas amplification), and the number of electrons and ions increases exponentially as the electric field supply electrode 132 is approached. Further, light generated at the time of collision of gas molecules with electrons is detected by the detector 117 as a signal 116 having secondary electron information, and is amplified by the amplifier 118. For example, a photomultiplier tube may be used as the detector 117 or the amplifier 118, or a photodiode may be used as the detector 117 and an amplifier circuit may be used as the amplifier 118. In the first embodiment, light is used as the signal 116 having secondary electron information. However, the electron flow or ion flow generated as a result of gas amplification may be detected by the detector 117 as the signal 116.
　上段偏向コイル１１１および下段偏向コイル１１２は偏向制御回路１２４によって制御されており、観察の目的に応じて、一次電子ビーム１０４の走査速度を変えることができる。例えば、Ｓ／Ｎの良い像を取得したい場合は、一次電子ビーム１０４の走査速度を遅くする。走査電子顕微鏡では、試料１１４上の正方形ないしは長方形の範囲を一次電子ビーム１０４で走査して、試料１１４上を走査する位置と、表示装置１２９で信号電子の強度を表示させる位置とを同期させることで像を得ている。そのため、一次電子ビーム１０４の走査速度が遅いと試料１１４に照射される一次電子ビーム１０４の量も多くなるため、取得できる信号１１６も多くなり、Ｓ／Ｎの良い像を得ることができる。通常、保存画像を得る場合は１フレーム当たり１０秒～数１００秒で一次電子ビーム１０４を試料１１４に走査する。 The upper deflection coil 111 and the lower deflection coil 112 are controlled by a deflection control circuit 124, and the scanning speed of the primary electron beam 104 can be changed according to the purpose of observation. For example, when it is desired to obtain an image with a good S / N, the scanning speed of the primary electron beam 104 is decreased. In the scanning electron microscope, a square or rectangular area on the sample 114 is scanned with the primary electron beam 104, and the position where the sample 114 is scanned is synchronized with the position where the display device 129 displays the intensity of the signal electrons. I got a statue at. For this reason, when the scanning speed of the primary electron beam 104 is low, the amount of the primary electron beam 104 irradiated on the sample 114 also increases, so that the number of signals 116 that can be acquired increases and an image with a good S / N can be obtained. Normally, when obtaining a stored image, the sample 114 is scanned with the primary electron beam 104 at 10 to several hundred seconds per frame.
　一方、試料１１４上の観察物を探したり、フォーカス調整を行ったりする際は、一次電子ビーム１０４の走査速度を速くする。試料台１１５の移動やフォーカス調整に対して、追従性よく表示装置１２９に表示させるためである。一般的にこのような場合は、１フレーム当たり数１０ミリ秒～１秒程度のスキャンが用いられる。このとき、検出器１１７や増幅器１１８の応答速度が、走査速度に比べて遅い場合は、隣接した表示ピクセルにおいて信号１１６のクロストークが生じ、表示画像上では像流れ等の原因となり、試料１１４で発生する二次電子や反射電子に起因する凹凸情報や組成情報が失われることとなる。 On the other hand, when searching for an observation object on the sample 114 or performing focus adjustment, the scanning speed of the primary electron beam 104 is increased. This is because the display device 129 displays the sample table 115 with good followability with respect to the movement of the sample stage 115 and the focus adjustment. In such a case, a scan of about several tens of milliseconds to one second per frame is generally used. At this time, when the response speed of the detector 117 or the amplifier 118 is slower than the scanning speed, crosstalk of the signal 116 occurs in the adjacent display pixels, causing image flow on the display image, and the sample 114. Concavity and convexity information and composition information resulting from the generated secondary electrons and reflected electrons are lost.
　例えば、一次電子ビーム１０４を１フレームあたり１６０ミリ秒で走査し、表示装置１２９に１２８０×９６０ピクセルで表示させる場合、１ピクセルあたりの一次電子ビーム１０４の走査時間は約１３０ナノ秒となる。したがって、このような高速スキャン時に情報を失わずに表示させるためには、検出器１１７の応答時間が１ピクセルあたりの一次電子ビーム１０４の走査時間よりも速い必要があり、さらに増幅器１１８が増幅回路によるものであれば、周波数帯域が１／１３０ナノ秒、すなわち７．７メガＨｚ以上のものが必要となる。 For example, when the primary electron beam 104 is scanned at 160 milliseconds per frame and displayed on the display device 129 at 1280 × 960 pixels, the scanning time of the primary electron beam 104 per pixel is about 130 nanoseconds. Therefore, in order to display information without losing information during such a high-speed scan, the response time of the detector 117 needs to be faster than the scan time of the primary electron beam 104 per pixel, and the amplifier 118 has an amplifier circuit. Therefore, a frequency band of 1/130 nanosecond, that is, 7.7 MHz or higher is required.
　試料周辺の残留ガス分子と二次電子とのガス増幅作用を用いて二次電子情報を含んだ画像を形成するＳＥＭにおいては、検出器の応答速度としてガス増幅作用による応答が主となる。ガス増幅による応答時間は通常、数１０マイクロ秒～数１０ミリ秒となるため、像流れのないＳＥＭ像を取得するためには走査速度を遅くして取得する必要がある。 In the SEM that forms an image including secondary electron information using the gas amplification action of residual gas molecules and secondary electrons around the sample, the response due to the gas amplification action is the main response speed of the detector. Since the response time due to gas amplification is usually several tens of microseconds to several tens of milliseconds, it is necessary to obtain the SEM image with no image flow at a low scanning speed.
　図２（ａ）から図２（ｅ）を用いて、本発明の走査電子顕微鏡の画像の像流れの抑制効果について説明する。図２（ａ）は、本発明における観察試料の一例を説明する図である。試料１１４は、銅メッシュ２０１と銅リング２０２で構成されている。図２（ｂ）は、本発明における像流れの一例を示す走査電子顕微鏡像であり、ガス増幅作用の結果発生する光を検出して取得した走査電子顕微鏡の画像の例を示す。図２（ｂ）は、一次電子ビーム１０４の走査速度を約９５ナノ秒／ピクセルとして、銅メッシュ２０１と銅リング２０２の画像を取得している。このとき１フレームあたり約８０ミリ秒のスキャンであり、図２（ｂ）は比較的速い走査速度で画像を取得した例である。また、試料１１４周辺の真空度は約５０Ｐａであり、銅メッシュ２０１と銅リング２０２の境界付近を観察している。一次電子ビーム１０４は画像の左から右へと走査している。図２（ｃ）は、走査電子顕微像の像流れを説明するための図２（ｂ）の模式図である。 2A to 2E, the effect of suppressing the image flow of the image of the scanning electron microscope of the present invention will be described. Fig.2 (a) is a figure explaining an example of the observation sample in this invention. The sample 114 includes a copper mesh 201 and a copper ring 202. FIG. 2B is a scanning electron microscope image showing an example of an image flow in the present invention, and shows an example of an image of a scanning electron microscope acquired by detecting light generated as a result of gas amplification. In FIG. 2B, images of the copper mesh 201 and the copper ring 202 are acquired at a scanning speed of the primary electron beam 104 of about 95 nanoseconds / pixel. At this time, scanning is about 80 milliseconds per frame, and FIG. 2B shows an example in which an image is acquired at a relatively high scanning speed. The degree of vacuum around the sample 114 is about 50 Pa, and the vicinity of the boundary between the copper mesh 201 and the copper ring 202 is observed. The primary electron beam 104 is scanning from the left to the right of the image. FIG. 2C is a schematic diagram of FIG. 2B for explaining the image flow of the scanning electron microscopic image.
　図２（ｄ）は、本発明における走査電子顕微像の一例を示す画像である。図２（ｄ）は、比較的遅いスキャンで観察した例として一次電子ビーム１０４の走査速度を約３４００ナノ秒／ピクセル、１フレームあたり約４秒の条件下で、図２（ｂ）と同一視野を走査速度以外は同一条件を観察した走査電子顕微像の一例を示す画像である。 FIG. 2 (d) is an image showing an example of a scanning electron microscopic image in the present invention. FIG. 2 (d) shows the same field of view as FIG. 2 (b) under the condition that the scanning speed of the primary electron beam 104 is about 3400 nanoseconds / pixel and about 4 seconds per frame as an example observed with a relatively slow scan. Is an image showing an example of a scanning electron microscopic image obtained by observing the same conditions except for the scanning speed.
　図２（ｂ）、（ｄ）を比較すると、速い一次電子ビーム１０４の走査速度で観察した図２（ｂ）には銅リング部において、図２（ｃ）に図示する像流れ部２０３が生じており、この像流れは、メッシュの空隙部２０４を走査している行が、像流れ部２０３として、本来の銅リング２０２部より暗くなっており、図の右側にいくにつれて像流れの暗さが薄くなっていることを図示している。これは、一次電子ビーム１０４の走査速度に対して、検出器の応答速度が遅れているため、銅メッシュ２０１の間の空隙部２０４が、走査方向である画像の左側から右側に流れて像流れ部２０３が表示されるためである。図２（ｄ）は、一次電子ビーム１０４の走査速度が比較的遅く、検出器の応答速度との差が小さくなるため、図２（ｂ）と比べ、像流れが減少し、走査電子顕微鏡像では、像流れがほとんど見られない。 2 (b) and 2 (d) are compared, the image flow portion 203 shown in FIG. 2 (c) is generated in the copper ring portion in FIG. 2 (b) observed at the high primary electron beam 104 scanning speed. In this image flow, the scanning line of the mesh void 204 is darker than the original copper ring 202 as the image flow portion 203, and the darkness of the image flow becomes closer to the right side of the figure. It shows that is thin. This is because, since the response speed of the detector is delayed with respect to the scanning speed of the primary electron beam 104, the gap portion 204 between the copper meshes 201 flows from the left side to the right side of the image in the scanning direction. This is because the part 203 is displayed. In FIG. 2D, since the scanning speed of the primary electron beam 104 is relatively slow and the difference from the response speed of the detector is small, the image flow is reduced as compared with FIG. Then, there is almost no image flow.
　図２（ｅ）は、本発明の像流れの抑制効果を示す走査電子顕微鏡像である。本実施例では、試料台用電源１２７を用いて、試料台１１５に電圧を印加し、さらに試料１１４に電圧を印加できる。また、試料台用電源１２７を用いて、試料台１１５、及び試料１１４に印加する電圧を調節することができる。図２（ｅ）は、試料台用電源１２７を用いて、試料１１４に－２０Ｖの電圧を印加して、図２（ｂ）と同一の一次電子ビームの１０４の走査速度である約９５ナノ秒／ピクセルで画像を取得した走査電子顕微鏡像である。図２（ｅ）では、図２（ｂ）で見られ、図２（ｃ）を用いて図示する像流れ部２０３が、ほぼ見られなくなっており、一次電子ビーム１０４の走査速度が速い条件下でも、像流れが抑制されている。 FIG. 2 (e) is a scanning electron microscope image showing the effect of suppressing the image flow of the present invention. In this embodiment, it is possible to apply a voltage to the sample stage 115 and further apply a voltage to the sample 114 using the power supply 127 for the sample stage. In addition, the voltage applied to the sample stage 115 and the sample 114 can be adjusted using the power supply 127 for the sample stage. FIG. 2 (e) shows that the scanning speed of 104 of the same primary electron beam as in FIG. 2 (b) is about 95 nanoseconds when a voltage of −20V is applied to the sample 114 using the power supply 127 for the sample stage. It is the scanning electron microscope image which acquired the image by / pixel. In FIG. 2 (e), the image flow part 203 seen in FIG. 2 (b) and illustrated using FIG. 2 (c) is almost not seen, and the scanning speed of the primary electron beam 104 is high. However, the image flow is suppressed.
　図３（ａ）は、シリコン（Ｓｉ）基板上に、白金（Ｐｔ）を蒸着した試料の走査電子顕微像を示す図である。図３（ａ）に示すようにシリコン（Ｓｉ）基板上に白金（Ｐｔ）を蒸着した試料を用意し、シリコンと白金の境界面を観察する画像を取得した。一次電子ビーム１０４の走査速度を、約９５ナノ秒／ピクセル、１フレームあたり約１６０ミリ秒の条件下で画像を取得した例である。図３は（ｂ）は、図３（ａ）のラインプロファイル取得部３０１の部分を画像の左側から右側に一次電子ビーム１０４を走査し取得したラインプロファイルを示す図である。シリコン、および白金部はほぼ一様であり、それぞれの領域ではほぼ一定の画像信号強度が得られると考えられるため、それらの境界での画像のラインプロファイルを取得することにより、ガス増幅の応答時間を定量的に評価した結果を示す図である。 FIG. 3A is a view showing a scanning electron microscopic image of a sample in which platinum (Pt) is vapor-deposited on a silicon (Si) substrate. As shown in FIG. 3A, a sample in which platinum (Pt) was vapor-deposited on a silicon (Si) substrate was prepared, and an image for observing the boundary surface between silicon and platinum was acquired. In this example, the image is acquired under the condition that the scanning speed of the primary electron beam 104 is about 95 nanoseconds / pixel and about 160 milliseconds per frame. FIG. 3B is a diagram showing a line profile obtained by scanning the portion of the line profile acquisition unit 301 in FIG. 3A from the left side to the right side of the image with the primary electron beam 104. Since the silicon and platinum parts are almost uniform and almost constant image signal intensity can be obtained in each region, the response time of gas amplification can be obtained by obtaining the line profile of the image at those boundaries. It is a figure which shows the result of having evaluated quantitatively.
　図４（ａ）は、試料に負電圧を印加した場合の検出器の応答時間曲線を示す図であり、図４（ｂ）は、試料に正電圧を印加した場合の検出器の応答時間曲線を示す図である。試料１１４に印加する電圧を－５Ｖから＋５Ｖまで１Ｖずつ変化させてシリコンと白金の境界面付近のラインプロファイルを取得した結果を示している。試料１１４周囲の真空度は５０Ｐａ、一次電子ビーム１０４の加速電圧は１５ｋＶ、作動距離は１０ｍｍである。試料１１４に印加する電圧を大きくすることにより、ラインプロファイルの立下りが速く、検出器の応答時間も短くなっている。その結果、像流れを抑制することができる。 FIG. 4A is a diagram showing a response time curve of the detector when a negative voltage is applied to the sample, and FIG. 4B is a response time curve of the detector when a positive voltage is applied to the sample. FIG. The graph shows the result of acquiring a line profile near the boundary surface between silicon and platinum by changing the voltage applied to the sample 114 in steps of 1V from -5V to + 5V. The degree of vacuum around the sample 114 is 50 Pa, the acceleration voltage of the primary electron beam 104 is 15 kV, and the working distance is 10 mm. By increasing the voltage applied to the sample 114, the fall of the line profile is fast and the response time of the detector is also shortened. As a result, image flow can be suppressed.
　図５は、試料に印加する電圧と検出器の応答時間の関係を示す図であり、図４のラインプロファイルから１００－１０％応答時間を求めた結果を示している。試料１１４に電圧を印加していない状態、すなわち試料１１４への印加電圧が０Ｖでは、応答時間は３１マイクロ秒であるが、試料１１４に＋５Ｖの電圧を印加することにより１６マイクロ秒、試料１１４に－５Ｖの電圧を印加することで１３マイクロ秒まで応答時間が改善した。また、本手法による測定では取得する画像の幅によって測定範囲が制限されてしまい、印加する電圧が低い場合は信号強度が定常状態となるまで取得できていないため、実際の応答時間の改善は今回の結果よりも大きいと考えられる。 FIG. 5 is a diagram showing the relationship between the voltage applied to the sample and the response time of the detector, and shows the result of obtaining the 100-10% response time from the line profile of FIG. When no voltage is applied to the sample 114, that is, when the voltage applied to the sample 114 is 0V, the response time is 31 microseconds, but by applying a voltage of + 5V to the sample 114, the response time is 16 microseconds. Response time improved to 13 microseconds by applying a voltage of -5V. In addition, in the measurement by this method, the measurement range is limited by the width of the image to be acquired, and when the applied voltage is low, it can not be acquired until the signal intensity reaches a steady state, so the actual response time is improved this time It is thought that it is larger than the result.
　図６（ａ）から図６（ｃ）を用いて、絶縁試料である紙を観察した場合の帯電と像流れの抑制効果について説明する。走査型電子顕微鏡では、一般的に絶縁物などの電気を通さない試料は一次電子ビーム１０４によって帯電してしまうため、観察するのが困難となる。絶縁試料への帯電を防ぐために、一次電子ビームの１０４の走査速度を速くすることで、１ピクセルあたりの一次電子ビーム照射量を小さくして帯電を軽減させる手法が取られている。しかし、一次電子ビーム１０４の走査速度を早くすると、検出器の応答速度が遅れて、像流れが生じやすい課題があったが、本実施例では、試料に電圧を印加することにより、絶縁試料の場合でも、像流れを抑制する効果が得られた例を説明する。本実施例での観察条件は、試料１１４周辺の真空度は５０Ｐａ、走査速度は９７２ナノ秒／ピクセルである。図６（ａ）は、本発明における絶縁試料を観察した際の画像の像流れの一例を示す走査電子顕微鏡像であり、絶縁試料である紙に電圧を印加していない場合、すなわち試料への印加電圧が０Ｖの走査電子顕微鏡像を示しており、試料表面の帯電による白とびや像流れが生じており、紙の繊維の構造が観察できていない。一方、図６（ｂ）は、本発明における絶縁試料に正電圧を印加し観察した際の画像の像流れの抑制を示す走査電子顕微鏡像であり、絶縁試料である紙に＋１０Ｖの電圧を印加した場合の走査電子顕微鏡像を示している。図６（ｃ）は、本発明における絶縁試料に負電圧を印加し観察した際の画像の像流れの抑制を示す走査電子顕微鏡像であり、絶縁試料である紙に－１０Ｖの電圧を印加した場合の走査電子顕微鏡像を示している。図６（ｂ）、および図６（ｃ）の両走査電子顕微鏡像とも、試料表面の帯電および像流れが抑制できており、絶縁試料である紙の繊維の構造を鮮明に確認することができる。 6A to 6C, the effect of suppressing charging and image flow when observing paper as an insulating sample will be described. In the scanning electron microscope, generally, a non-electrically conductive sample such as an insulator is charged by the primary electron beam 104, so that it is difficult to observe. In order to prevent charging of the insulating sample, a method of reducing charging by reducing the primary electron beam irradiation amount per pixel by increasing the scanning speed of the primary electron beam 104 is used. However, when the scanning speed of the primary electron beam 104 is increased, the response speed of the detector is delayed, and there is a problem that image flow is likely to occur. In this embodiment, by applying a voltage to the sample, Even in this case, an example in which the effect of suppressing the image flow is obtained will be described. The observation conditions in this example are that the degree of vacuum around the sample 114 is 50 Pa, and the scanning speed is 972 nanoseconds / pixel. FIG. 6A is a scanning electron microscope image showing an example of the image flow of an image when the insulating sample in the present invention is observed. In the case where no voltage is applied to the paper as the insulating sample, that is, to the sample. A scanning electron microscopic image with an applied voltage of 0 V is shown. Overexposure and image flow are caused by charging of the sample surface, and the structure of paper fibers cannot be observed. On the other hand, FIG. 6B is a scanning electron microscope image showing suppression of image flow of an image when a positive voltage is applied to the insulating sample in the present invention and observed, and a voltage of +10 V is applied to the paper as the insulating sample. A scanning electron microscope image is shown. FIG. 6C is a scanning electron microscope image showing suppression of image flow of an image when a negative voltage is applied to the insulating sample in the present invention and observed, and a voltage of −10 V is applied to the paper as the insulating sample. The scanning electron microscope image in the case is shown. Both the scanning electron microscopic images of FIG. 6B and FIG. 6C can suppress charging of the sample surface and image flow, and the structure of the fiber of the paper that is the insulating sample can be clearly confirmed. .
　図２～図６では、ガス増幅の結果発生する光を検出する検出器を用いた効果について説明してきたが、他の検出方式の検出器においても同様な像流れ抑制効果を得ることができる。 2 to 6, the effect of using a detector that detects light generated as a result of gas amplification has been described, but a similar image flow suppression effect can also be obtained with detectors of other detection methods.
　図７（ａ）から図７（ｅ）を用いて、イオン電流検出型のガス増幅現象を利用した検出器における像流れ抑制効果を説明する。本実施例では、ガス増幅の結果得られるイオンを検出する検出器において、試料に電圧を印加することによる像流れの抑制効果の例を示している。試料１１４としては、図２（ａ）から図２（ｅ）と同様に銅メッシュ２０１と銅リング２０２を用いて、走査電子顕微鏡による観察を行っている。試料１１４周辺の真空度は５０Ｐａ、走査速度は１．５６マイクロ秒／ピクセルである。 7A to 7E, the image flow suppression effect in the detector using the ion current detection type gas amplification phenomenon will be described. In the present embodiment, an example of the effect of suppressing image flow by applying a voltage to a sample in a detector that detects ions obtained as a result of gas amplification is shown. As the sample 114, the observation with a scanning electron microscope is performed using the copper mesh 201 and the copper ring 202 similarly to FIGS. 2 (a) to 2 (e). The degree of vacuum around the sample 114 is 50 Pa, and the scanning speed is 1.56 microseconds / pixel.
　図７（ａ）は、本発明における画像の像流れの一例を示す走査電子顕微鏡であり、試料への印加電圧が０Ｖの際の、銅メッシュ２０１と銅リング２０２を観察した走査電子顕微鏡像である。図７（ｂ）は、走査電子顕微鏡の画像の像流れの一例を説明するための図７（ａ）の模式図である。図７（ａ）では、上述した理由により、銅リング２０２部において、図７（ｂ）に図示する像流れ部２０３が見られる。図７（ａ）も一次電子ビーム１０４を走査電子顕微鏡像の左から右方向へ走査しており、一次電子ビーム１０４走査速度に対して、検出器の応答速度が遅れているため、銅メッシュ２０１の間の空隙部２０４が、走査方向である画像の左側から右側に流れて像流れ部２０３が表示されるためである。 FIG. 7A is a scanning electron microscope showing an example of the image flow of the image in the present invention, and is a scanning electron microscope image obtained by observing the copper mesh 201 and the copper ring 202 when the applied voltage to the sample is 0V. is there. FIG. 7B is a schematic diagram of FIG. 7A for explaining an example of the image flow of the image of the scanning electron microscope. In FIG. 7A, the image flow portion 203 shown in FIG. 7B is seen in the copper ring 202 portion for the reason described above. 7A also scans the primary electron beam 104 from the left to the right of the scanning electron microscope image, and the response speed of the detector is delayed with respect to the primary electron beam 104 scanning speed. This is because the gap portion 204 between the two flows from the left side to the right side of the image in the scanning direction and the image flow portion 203 is displayed.
　図７（ｃ）は、本発明における試料に正電圧を印加した場合の走査電子顕微鏡像であり、図７（ａ）の画像取得と同条件である走査速度は１．５６マイクロ秒／ピクセルで、試料に＋１０Ｖの正電圧を印加した場合の走査電子顕微鏡像である。また、図７（ｄ）は、本発明における試料に負電圧を印加した場合の走査電子顕微鏡像であり、図７（ａ）の画像取得と同条件である走査速度は１．５６マイクロ秒／ピクセルで、試料に－１０Ｖの負電圧を印加した場合の走査電子顕微鏡像である。図７（ｅ）は、走査電子顕微鏡の画像の像流れの抑制効果を説明するための図７（ｃ）および図７（ｄ）の模式図である。図７（ｃ）および図７（ｄ）の両走査電子顕微鏡像ともに像流れが抑制できており、銅リング２０２部おいて図７（ｂ）に図示する像流れ部２０３がなくなるとともに、銅メッシュの鮮明な構造や図７（ｅ）に図示する銅メッシュ上の異物７０１まで確認できるようになった。また、像流れ抑制の効果は試料へ印加する電圧の正負に関係なく得られる。 FIG. 7C is a scanning electron microscope image when a positive voltage is applied to the sample in the present invention, and the scanning speed under the same conditions as the image acquisition in FIG. 7A is 1.56 microseconds / pixel. It is a scanning electron microscope image at the time of applying a + 10V positive voltage to a sample. FIG. 7D is a scanning electron microscope image when a negative voltage is applied to the sample in the present invention, and the scanning speed under the same conditions as the image acquisition in FIG. 7A is 1.56 microseconds / second. It is a scanning electron microscope image when a negative voltage of −10 V is applied to a sample in a pixel. FIG. 7E is a schematic diagram of FIG. 7C and FIG. 7D for explaining the effect of suppressing the image flow of the image of the scanning electron microscope. In both scanning electron microscope images of FIGS. 7C and 7D, the image flow can be suppressed, and the image flow portion 203 shown in FIG. As a result, it is possible to confirm the clear structure and the foreign matter 701 on the copper mesh shown in FIG. Further, the effect of suppressing the image flow can be obtained regardless of whether the voltage applied to the sample is positive or negative.
　実施例１では、試料１１４に電圧を印加することによる像流れの抑制効果について述べた。しかし、像流れ抑制のため試料１１４に電圧を印加することで、ＳＥＭ像が暗くなり画像のＳ／Ｎが悪化する場合がある。試料１１４に電圧を印加することで像流れを抑制できる反面、ガス増幅が作用する時間が短くなり、ガス増幅による信号も少なくなるためと考えられる。しかし、実際にユーザーが走査電子顕微鏡を扱う際は、視野探しやフォーカス調整、画像の保存といった場合に応じてスキャンの種類を変えながら使用することとなる。一次電子ビーム１０４の走査速度の変更は、グラフィカルユーザーインターフェース（ＧＵＩ）上に表示されたボタンや、機械的なボタンスイッチなどによって操作できるようになっている。 In Example 1, the effect of suppressing image flow by applying a voltage to the sample 114 was described. However, when a voltage is applied to the sample 114 to suppress image flow, the SEM image may become dark and the S / N of the image may deteriorate. Although the image flow can be suppressed by applying a voltage to the sample 114, it is considered that the time during which the gas amplification acts is shortened and the signal due to the gas amplification is also reduced. However, when the user actually handles the scanning electron microscope, the user uses the scanning electron microscope while changing the type of scanning according to the case of searching the visual field, adjusting the focus, or saving the image. The scanning speed of the primary electron beam 104 can be changed by a button displayed on a graphical user interface (GUI), a mechanical button switch, or the like.
　図８は、本発明におけるグラフィックユーザーインターフェース（ＧＵＩ）の例を示す図である。一般的な走査電子顕微鏡では視野探し等で使用する高速スキャンボタン８０１、画像の確認やフォーカス等の微調整で使用する低速スキャンボタン８０２、フォーカスの調整で使用する視野制限スキャンボタン８０３、画像表示部８０４、一次電子ビーム１０４のフォーカスを調整するフォーカス調整用スライダ８０５、一次電子ビーム１０４の非点を調整する非点調整用スライダ８０６等が設けられて、ユーザーが様々な一次電子ビーム１０４の走査条件を切り替えながら、走査電子顕微鏡で取得した画像を表示することが出来るようになっている。 FIG. 8 is a diagram showing an example of a graphic user interface (GUI) in the present invention. In a general scanning electron microscope, a high-speed scan button 801 used for visual field search, a low-speed scan button 802 used for image confirmation and fine adjustment of focus, a field-restricted scan button 803 used for focus adjustment, an image display unit 804, a focus adjustment slider 805 for adjusting the focus of the primary electron beam 104, an astigmatism adjustment slider 806 for adjusting the astigmatism of the primary electron beam 104, and the like, are provided so that the user can scan various primary electron beam 104 scanning conditions. The image acquired by the scanning electron microscope can be displayed while switching between.
　ガス増幅現象を利用した検出器を用い観察する場合、観察時に像流れが発生するのは、ガス増幅現象の応答速度より１ピクセル当たりの一次電子ビーム１０４の走査時間が短い高速スキャンにて観察する場合であり、ガス増幅現象の応答速度より１ピクセル当たりの一次電子ビーム１０４の走査時間が長いような低速なスキャンにおいて像流れは発生しない。すなわち、像流れは高速スキャン時のみ抑制出来れば良い。一方、前述したとおり像流れの抑制のため、試料１１４に電圧を印加することで、ガス増幅による信号が小さくなり画像のＳ／Ｎが悪化する場合がある。そのため、高速スキャン時のみに試料１１４に電圧を印加し、低速スキャン時には試料１１４に電圧を印加しないように制御することで、低速スキャン時はＳ／Ｎを損なわず、また、高速スキャン時には像流れを抑制することができる。 When observing using a detector utilizing the gas amplification phenomenon, image flow occurs during observation because the scanning time of the primary electron beam 104 per pixel is shorter than the response speed of the gas amplification phenomenon. In this case, image flow does not occur in a slow scan in which the scan time of the primary electron beam 104 per pixel is longer than the response speed of the gas amplification phenomenon. That is, it is only necessary that the image flow can be suppressed only during high speed scanning. On the other hand, as described above, in order to suppress the image flow, when a voltage is applied to the sample 114, the signal due to gas amplification becomes small, and the S / N of the image may deteriorate. Therefore, by controlling so that a voltage is applied to the sample 114 only at the time of high-speed scanning and not applying voltage to the sample 114 at the time of low-speed scanning, the S / N is not impaired at the time of low-speed scanning, and the image flow is at the time of high-speed scanning. Can be suppressed.
　また、試料１１４に印加する電圧の大きさに応じて像流れ抑制の効果の大小も変化するため、一次電子ビーム１０４の走査速度に応じて試料１１４に印加する電圧を変化させても良い。高速スキャン時に試料１１４に印加した電圧よりグラウンドに近い電圧を低速スキャン時に試料１１４に印加することで、像流れを抑制できる。 In addition, since the magnitude of the image flow suppression effect changes according to the magnitude of the voltage applied to the sample 114, the voltage applied to the sample 114 may be changed according to the scanning speed of the primary electron beam 104. By applying a voltage closer to the ground than the voltage applied to the sample 114 during high-speed scanning to the sample 114 during low-speed scanning, image flow can be suppressed.
　さらに、試料１１４に印加する電圧を変化させるとガス増幅現象の様子が変化し、画像の輝度も変化するため、その輝度変化を補償するために電界供給電極１３２の電圧を一次電子ビーム１０４の走査速度に応じて変化させたり、もしくは自動的に画像の明るさを調整する処理を一次電子ビーム１０４走査速度の変更と同時に実行させてもよい。他には、増幅器１１８の増幅度を変更するように制御するのも有効であると考えられる。 Further, when the voltage applied to the sample 114 is changed, the state of the gas amplification phenomenon changes and the luminance of the image also changes. Therefore, the voltage of the electric field supply electrode 132 is scanned with the primary electron beam 104 to compensate for the luminance change. The process of changing the speed according to the speed or automatically adjusting the brightness of the image may be executed simultaneously with the change of the scanning speed of the primary electron beam 104. In addition, it is considered effective to control the amplification degree of the amplifier 118 to be changed.
１００：走査電子顕微鏡システム、：１０１：フィラメント、１０２：ウェネルト、１０３：陽極、１０４：一次電子ビーム、１０５：上段ガンアライメントコイル、１０６：下段ガンアライメントコイル、１０７：第一集束レンズ、１０８：第二集束レンズ、１０９：対物絞り、１１０：アライナー、１１１：上段偏向コイル、１１２：下段偏向コイル、１１３：対物レンズ、１１４：試料、１１５：試料台、１１６：信号、１１７：検出器、１１８：増幅器、１１９：高電圧制御回路、１２０：ガンアライメント制御回路、１２１：第一集束レンズ制御回路、１２２：第二集束レンズ制御回路、１２３：アライナー制御回路、１２４：偏向制御回路、１２５：対物レンズ制御回路、１２６：電界供給電極用電源、１２７：試料台用電源、１２８：コンピュータ、１２９：表示装置、１３０：記憶手段、１３１：入力手段、１３２：電界供給電極、２０１：銅メッシュ、２０２：銅リング、２０３：像流れ部、２０４：空隙部、３０１：ラインプロファイル取得部、７０１：異物、８０１：高速スキャンボタン、８０２：低速スキャンボタン、８０３：視野制限スキャンボタン、８０４：画像表示部、８０５：フォーカス調整用スライダ、８０６：非点調整用スライダ 100: Scanning electron microscope system: 101: Filament, 102: Wehnelt, 103: Anode, 104: Primary electron beam, 105: Upper gun alignment coil, 106: Lower gun alignment coil, 107: First focusing lens, 108: First Double focusing lens, 109: objective diaphragm, 110: aligner, 111: upper deflection coil, 112: lower deflection coil, 113: objective lens, 114: sample, 115: sample stage, 116: signal, 117: detector, 118: Amplifier: 119: High voltage control circuit, 120: Gun alignment control circuit, 121: First focusing lens control circuit, 122: Second focusing lens control circuit, 123: Aligner control circuit, 124: Deflection control circuit, 125: Objective lens Control circuit, 126: power supply for electric field supply electrode, 127: power supply for sample table, 28: computer, 129: display device, 130: storage means, 131: input means, 132: electric field supply electrode, 201: copper mesh, 202: copper ring, 203: image flow portion, 204: gap portion, 301: line profile Acquisition unit, 701: foreign object, 801: high-speed scan button, 802: low-speed scan button, 803: field-of-view restriction scan button, 804: image display unit, 805: slider for focus adjustment, 806: slider for astigmatism adjustment

Claims (11)

  1. 　電子ビームを試料に照射する照射光学系と、
    　試料台と、
    　前記電子ビームの照射により発生する電子に作用する電界を供給する電界供給電極と、
    　前記試料に電圧を印加する電源と、を備えることを特徴とする走査電子顕微鏡。     An irradiation optical system for irradiating the sample with an electron beam;
    A sample stage;
    An electric field supply electrode for supplying an electric field acting on electrons generated by irradiation of the electron beam;
    And a power source for applying a voltage to the sample.
  2. 　請求項１記載の走査電子顕微鏡において、
    　前記電源は、正負の電圧を前記試料に印加することを特徴とする走査電子顕微鏡。     The scanning electron microscope according to claim 1,
    The power source applies a positive or negative voltage to the sample.
  3. 　請求項１記載の走査電子顕微鏡において、
    　前記電子ビームの照射により発生する電子が二次電子であることを特徴とする走査電子顕微鏡。     The scanning electron microscope according to claim 1,
    A scanning electron microscope characterized in that electrons generated by irradiation with the electron beam are secondary electrons.
  4. 　電子ビームを試料に照射する照射光学系と、
    　試料台と、
    　前記電子ビームの照射により発生する電子に作用する電界を供給する電界供給電極と、
    　前記電子ビームの走査速度を変更する偏向コイルと
    　前記試料に電圧を印加する電源と、を備え、
    　前記試料に第１の電圧を印加して第１の走査速度で撮像し、前記試料に前記第１の電圧よりもグラウンドに近い第２の電圧を印加して前記第１の走査速度よりも遅い第２の走査速度で撮像することを特徴とする走査電子顕微鏡。     An irradiation optical system for irradiating the sample with an electron beam;
    A sample stage;
    An electric field supply electrode for supplying an electric field acting on electrons generated by irradiation of the electron beam;
    A deflection coil for changing the scanning speed of the electron beam, and a power source for applying a voltage to the sample,
    A first voltage is applied to the sample to image at a first scanning speed, and a second voltage closer to the ground is applied to the sample than the first voltage to be slower than the first scanning speed. A scanning electron microscope characterized in that imaging is performed at a second scanning speed.
  5. 　請求項４記載の走査電子顕微鏡において、
    　前記電子ビームの照射により発生する電子が二次電子であることを特徴とする走査電子顕微鏡。     The scanning electron microscope according to claim 4, wherein
    A scanning electron microscope characterized in that electrons generated by irradiation with the electron beam are secondary electrons.
  6. 　請求項４記載の走査電子顕微鏡において、
    　前記電子ビームの走査速度を変更する際に、前記電界供給電極の電圧を制御することを特徴とする走査電子顕微鏡。     The scanning electron microscope according to claim 4, wherein
    A scanning electron microscope characterized by controlling the voltage of the electric field supply electrode when changing the scanning speed of the electron beam.
  7. 　請求項４記載の走査電子顕微鏡において、
    　前記電子ビームの走査速度を変更する際に、撮像される画像の明るさを自動的に調整して撮像することを特徴とする走査電子顕微鏡。     The scanning electron microscope according to claim 4, wherein
    A scanning electron microscope characterized in that when changing the scanning speed of the electron beam, the brightness of an image to be picked up is automatically adjusted and picked up.
  8. 　試料を試料台に載置し、
    　電子ビームを試料に照射し、
    　前記電子ビームの照射により発生する電子に作用する電界を電界供給電極により供給し、
    　前記試料に第１の電圧を印加して第１の走査速度で撮像し、前記試料に前記第１の電圧よりもグラウンドに近い第２の電圧を印加して前記第１の走査速度よりも遅い第２の走査速度に該走査速度を変更し、撮像することを特徴とする走査電子顕微鏡の撮像方法。     Place the sample on the sample stage,
    Irradiate the sample with an electron beam,
    An electric field acting on electrons generated by the electron beam irradiation is supplied by an electric field supply electrode;
    A first voltage is applied to the sample to image at a first scanning speed, and a second voltage closer to the ground is applied to the sample than the first voltage to be slower than the first scanning speed. An imaging method for a scanning electron microscope, wherein the imaging is performed by changing the scanning speed to a second scanning speed.
  9. 　請求項８記載の走査電子顕微鏡の撮像方法において、
    　前記電子ビームの照射により発生する電子が二次電子であることを特徴とする走査電子顕微鏡の撮像方法。     The scanning electron microscope imaging method according to claim 8,
    An imaging method of a scanning electron microscope, wherein electrons generated by the irradiation of the electron beam are secondary electrons.
  10. 　請求項８記載の走査電子顕微鏡の撮像方法において、
    　前記電子ビームの走査速度を変更する際に、前記電界供給電極の電圧を制御することを特徴とする走査電子顕微鏡の撮像方法。     The scanning electron microscope imaging method according to claim 8,
    An imaging method of a scanning electron microscope, wherein the voltage of the electric field supply electrode is controlled when changing the scanning speed of the electron beam.
  11. 　請求項８記載の走査電子顕微鏡の撮像方法において、
    　前記電子ビームの走査速度を変更する際に、撮像される画像の明るさを自動的に調整して撮像することを特徴とする走査電子顕微鏡の撮像方法。     The scanning electron microscope imaging method according to claim 8,
    An imaging method for a scanning electron microscope, wherein when changing the scanning speed of the electron beam, the brightness of an image to be captured is automatically adjusted for imaging.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013080722A (en) * 2006-01-25 2013-05-02 Ebara Corp Sample surface inspection method and sample surface inspection apparatus
JP2013178879A (en) * 2012-02-28 2013-09-09 Hitachi High-Technologies Corp Scanning electron microscope

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013080722A (en) * 2006-01-25 2013-05-02 Ebara Corp Sample surface inspection method and sample surface inspection apparatus
JP2013178879A (en) * 2012-02-28 2013-09-09 Hitachi High-Technologies Corp Scanning electron microscope

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