JP6920539B2 - Scanning electron microscope and its imaging method - Google Patents

Description

The present invention utilizes the amplification of secondary electrons by residual molecules around the sample among the secondary electron observation methods using a scanning electron microscope (hereinafter, SEM), and the electrons or ions amplified by the amplification, 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 secondary electron images in high-speed scanning obtained by SEM.

Usually, an Everhard-Tornley detector (ET detector) is used to detect secondary electrons with a scanning electron microscope. In this method, secondary electrons generated on the surface of a sample are accelerated at a high voltage of about 10 kV, converted into light by a scintillator, and detected. Since such an Everhard-Tornley detector uses a high voltage of about 10 kV, the sample chamber must have a vacuum degree of 10 ^-1 Pa or less to generate a discharge due to the high voltage and cannot be used.

On the other hand, there is a method of observing secondary electrons by setting the pressure inside the sample chamber to about several Pa to several 1000 Pa, which is used to reduce the charge on the sample surface or to sample a liquid that evaporates in a high vacuum. It is used when observing in the state of being contained in. In this case, as a method of observing secondary electrons, a method of amplifying secondary electrons by utilizing residual gas molecules around the sample is well known.

Patent Document 1 discloses a method of 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 method of obtaining a secondary electron image by detecting light generated by collision between secondary electrons and residual gas molecules.

Japanese Unexamined Patent Publication No. 2006-228586 U.S. Pat. No. US4992662

The response speed of the SEM detector affects the image quality during high-speed scanning. In SEM, an electron beam is scanned on a sample, and the magnitude of the signal amount of signal electrons such as secondary electrons generated at that time is displayed as an image. The speed at which the electron beam is scanned can be changed according to the purpose of observation. High-speed scanning is used to search the field of view and reduce charging. For example, TV scanning scans an electron beam 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, image flow occurs and the detailed structure on the sample cannot be confirmed.

In the secondary electron detector using gas amplification, the electrons are amplified exponentially by the interaction between the secondary electrons and the residual molecules around the sample. The response speed in a detector utilizing such a gas amplification phenomenon is mainly determined by two factors. One is the deterioration of the response speed caused by the gas amplification phenomenon. In gas amplification, in addition to electron and ion amplification phenomena, multiple phenomena such as recombination of electrons and ions occur at the same time. Therefore, it is known that it takes some time for the number of electrons and ions around the sample to settle in 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 the signal is very small, so it is necessary to amplify it in order to obtain an SEM image. When detecting ions and electrons, the signal is amplified by an electronic circuit, and the amplification factor is generally increased so as not to be affected by disturbance. However, when the amplification factor is increased, the frequency band becomes smaller (<100 kHz), so that the response speed becomes worse. On the other hand, in the detector that detects the light generated as a result of gas amplification, the signal can be amplified using an amplifier with a fast response speed (<100 nanoseconds) such as a photomultiplier tube. In this case, the response speed by gas amplification is used. It is important to improve.

By providing an ion detection electrode near the electric field supply electrode, the response speed of the gas amplification action is improved, but in high-speed scanning, image flow due to gas amplification also occurs. On the other hand, ^{in the Everhard-Tornley detector used for high vacuum of 10 -1} Pa or less, such an image flow does not occur because the gas amplification action is not used. 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, but there is no method for obtaining a sufficient response speed for the detector using gas amplification. Therefore, it is an urgent task to improve the response speed of the detector using the gas amplification action.

In the scanning electron microscope of the present invention, an irradiation optical system that irradiates a sample with an electron beam, a sample table, an electric field supply electrode that supplies an electric field that acts on electrons generated by irradiation of the electron beam, and a scanning speed of the electron beam are used. A deflection coil for controlling and a power supply for applying a voltage to the sample are provided, and a voltage closer to the ground than the voltage applied to the sample when the scanning speed of the electron beam is high is applied to the sample when the scanning speed of the electron beam is slow. Then, the above-mentioned problem is solved.

According to the present invention, in an SEM that forms an image containing secondary electron information by using the gas amplification action of residual gas molecules around a sample and secondary electrons, the response speed of the detector is faster than that of a conventional detection system. Can be realized.

It is a figure which shows the 1st Example of the scanning electron microscope based on this invention. It is a figure explaining an example of the observation sample in this invention. It is a scanning electron microscope image which shows an example of the image flow of an image in this invention. It is a schematic diagram of FIG. 2B for explaining the image flow of the scanning electron microscope image. It is an image which shows an example of the scanning electron microscope image in this invention. It is a scanning electron microscope image which shows the effect of suppressing the image flow of this invention. It is a figure which shows the scanning electron microscope image of the sample which was vapor-deposited platinum (Pt) on the silicon (Si) substrate. It is a figure which shows the line profile acquired from the image of a scanning electron microscope. It is a figure which shows the response time curve of a detector when a negative voltage is applied to a sample. It is a figure which shows the response time curve of a detector when a positive voltage is applied to a sample. It is a figure which shows the relationship between the voltage applied to a sample, and the response time of a detector. It is a scanning electron microscope image which shows an example of the image flow of the image when observing the insulation sample in this invention. It is a scanning electron microscope image which shows the suppression of the image flow of an image when observing by applying a positive voltage to an insulating sample in this invention. 6 is a scanning electron microscope image showing suppression of image flow of an image when a negative voltage is applied to an insulated sample in the present invention for observation. It is a scanning electron microscope which shows an example of the image flow of an image in this invention. It is a schematic diagram of FIG. 7A for explaining an example of the image flow of the image of a scanning electron microscope. It is a scanning electron microscope image when a positive voltage is applied to a sample in this invention. It is a scanning electron microscope image when a negative voltage is applied to a sample in this invention. It 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. It is a figure which shows the example of the graphic user interface (GUI) in this invention.

In the following embodiments, when necessary for convenience, the description will be divided into a plurality of sections or embodiments, but unless otherwise specified, they are not unrelated to each other, and one is the other. There is a relationship between some or all of the modifications, details, supplementary explanations, etc.

Further, in the drawings used in the following embodiments, hatching may be added to make the drawings easier to see even if they are plan views. Further, in all the drawings for explaining the following embodiments, those having the same function are, in principle, given the same reference numerals, and the repeated description thereof will be omitted. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a first embodiment of a scanning electron microscope based on the present invention. The scanning electron microscope system 100 includes a filament 101, a Wenert 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, and an aligner. 110, upper deflection coil 111, lower deflection coil 112, objective lens 113, sample 114, sample base 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, power supply 126 for electric field supply electrode, power supply 127 for sample stand, computer 128, display device 129, storage means 130 , Input means 131, and electric field supply electrode 132.

In the scanning electron microscope, a desired voltage is applied to the filament 101, the Wenert 102, and the anode 103 by the high voltage control circuit 119, 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 created 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 the gas molecules around the sample to generate electron-ion pairs. The secondary electrons and the electrons generated by the collision with the gas molecule are directed toward the electric field supply electrode 132 while repeatedly colliding with the gas molecule.

This process causes electron avalanche (gas amplification), and the number of electrons and the number of ions increase exponentially as it approaches the electric field supply electrode 132. Further, the light generated when a gas molecule collides with an electron 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, but 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 the 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 acquire an image having a good S / N, the scanning speed of the primary electron beam 104 is slowed down. In the scanning electron microscope, a square or rectangular area on the sample 114 is scanned by the primary electron beam 104, and the position of scanning on the sample 114 and the position of displaying the intensity of signal electrons on the display device 129 are synchronized. I'm getting a statue at. Therefore, if the scanning speed of the primary electron beam 104 is slow, the amount of the primary electron beam 104 irradiated to the sample 114 also increases, so that the number of signals 116 that can be acquired increases, and a good image of S / N can be obtained. Usually, when a preserved image is obtained, the primary electron beam 104 is scanned over the sample 114 in 10 seconds to several hundred seconds per frame.

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 for displaying on the display device 129 with good followability to the movement of the sample table 115 and the focus adjustment. Generally, in such a case, a scan of several tens of milliseconds to one second per frame is used. At this time, if 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, which causes image flow or the like on the display image, and the sample 114 Concavo-convex information and composition information caused by the generated secondary electrons and backscattered electrons will be lost.

For example, when the primary electron beam 104 is scanned in 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 scanning time of the primary electron beam 104 per pixel, and the amplifier 118 is an amplifier circuit. If the frequency band is 1/130 nanoseconds, that is, 7.7 megaHz or more is required.

In an SEM that forms an image containing secondary electron information by using the gas amplification action of residual gas molecules around the sample and secondary electrons, the response speed of the detector is mainly the response by the gas amplification action. Since the response time due to gas amplification is usually several tens of microseconds to several tens of milliseconds, it is necessary to slow down the scanning speed in order to acquire an SEM image without image flow.

The effect of suppressing the image flow of the image of the scanning electron microscope of the present invention will be described with reference to FIGS. 2 (a) and 2 (e). FIG. 2A is a diagram illustrating an example of an observation sample in the present invention. Sample 114 is composed of a copper mesh 201 and a copper ring 202. FIG. 2B is a scanning electron microscope image showing an example of the image flow in the present invention, and shows an example of a scanning electron microscope image obtained by detecting the light generated as a result of the gas amplification action. In FIG. 2B, images of the copper mesh 201 and the copper ring 202 are acquired with the scanning speed of the primary electron beam 104 being about 95 nanoseconds / pixel. At this time, the scan is about 80 milliseconds per frame, and FIG. 2B shows an example in which an image is acquired at a relatively high scanning speed. Further, 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 left to right in the image. FIG. 2C is a schematic view of FIG. 2B for explaining the image flow of the scanning electron microscope image.

FIG. 2D is an image showing an example of a scanning electron microscope image in the present invention. FIG. 2D shows the same field of view as FIG. 2B 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 by a relatively slow scan. This is an image showing an example of a scanning electron microscope image in which the same conditions are observed except for the scanning speed.

Comparing FIGS. 2 (b) and 2 (d), in FIG. 2 (b) observed at a high scanning speed of the primary electron beam 104, the image flow portion 203 shown in FIG. 2 (c) is generated in the copper ring portion. In this image flow, the line scanning the gap 204 of the mesh is darker than the original copper ring 202 as the image flow part 203, and the image flow becomes darker toward the right side of the figure. Is shown to be thinner. This is because the response speed of the detector is delayed with respect to the scanning speed of the primary electron beam 104, so that the gap 204 between the copper mesh 201 flows from the left side to the right side of the image in the scanning direction to flow the image. This is because unit 203 is displayed. In FIG. 2D, the scanning speed of the primary electron beam 104 is relatively slow, and the difference from the response speed of the detector is small. Therefore, the image flow is reduced as compared with FIG. 2B, and the scanning electron microscope image is shown. Then, the image flow is hardly seen.

FIG. 2E is a scanning electron microscope image showing the effect of suppressing the image flow of the present invention. In this embodiment, the sample table power supply 127 can be used to apply a voltage to the sample table 115 and further to the sample 114. Further, the voltage applied to the sample table 115 and the sample 114 can be adjusted by using the sample table power supply 127. FIG. 2 (e) shows a scanning speed of 104 of the same primary electron beam as in FIG. 2 (b) of about 95 nanoseconds by applying a voltage of −20 V to the sample 114 using the sample table power supply 127. / It is a scanning electron microscope image obtained by acquiring an image in pixels. In FIG. 2 (e), the image flow portion 203 which is seen in FIG. 2 (b) and is illustrated by using FIG. 2 (c) is almost disappeared, and the scanning speed of the primary electron beam 104 is high. However, the image flow is suppressed.

FIG. 3A is a diagram showing a scanning electron microscope 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 interface between silicon and platinum was acquired. This is an example in which an 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. 3 (b) is a diagram showing a line profile acquired by scanning the portion of the line profile acquisition unit 301 of FIG. 3 (a) from the left side to the right side of the image by scanning the primary electron beam 104. Since the silicon and platinum parts are almost uniform and it is considered that almost constant image signal intensity can be obtained in each region, the response time of gas amplification is obtained by acquiring the line profile of the image at the boundary between them. It is a figure which shows the result of having quantitatively evaluated.

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. It is a figure which shows. The result of acquiring the line profile near the boundary surface between silicon and platinum by changing the voltage applied to the sample 114 by 1V from −5V to + 5V is shown. 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 short. As a result, the image flow can be suppressed.

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 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 0 V, the response time is 31 microseconds, but by applying a voltage of + 5 V to the sample 114, it takes 16 microseconds to the sample 114. By applying a voltage of -5V, the response time was improved up to 13 microseconds. 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 cannot be acquired until the signal strength becomes a steady state, so the actual improvement of the response time is this time. It is considered to be larger than the result of.

The effect of suppressing charge and image flow when observing paper as an insulating sample will be described with reference to FIGS. 6 (a) to 6 (c). In a scanning electron microscope, a sample that does not conduct electricity, such as an insulator, is generally charged by the primary electron beam 104, which makes it difficult to observe. In order to prevent charging of the insulated sample, a method is adopted in which the scanning speed of 104 of the primary electron beam is increased to reduce the irradiation amount of the primary electron beam per pixel to reduce the charging. However, when the scanning speed of the primary electron beam 104 is increased, the response speed of the detector is delayed and image flow is likely to occur. However, in this embodiment, by applying a voltage to the sample, the insulating sample is subjected to a problem. 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 the image when observing the insulating sample in the present invention, and is a case where no voltage is applied to the paper which is the insulating sample, that is, to the sample. It shows a scanning electron microscope image with an applied voltage of 0 V, and whiteout and image flow occur due to charging on 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 the image when a positive voltage is applied to the insulated sample and observed in the present invention, and a voltage of + 10 V is applied to the paper which is the insulated sample. The scanning electron microscope image is shown. FIG. 6 (c) is a scanning electron microscope image showing suppression of image flow of an image when a negative voltage is applied to an insulated sample and observed in the present invention, and a voltage of −10 V is applied to paper which is an insulated sample. The scanning electron microscope image of the case is shown. In both the scanning electron microscope images of FIGS. 6 (b) and 6 (c), the charge and image flow on the sample surface can be suppressed, and the structure of the paper fiber as the insulating sample can be clearly confirmed. ..

Although FIGS. 2 to 6 have described the effect of using a detector that detects the light generated as a result of gas amplification, the same image flow suppression effect can be obtained with a detector of another detection method.

The effect of suppressing the image flow in the detector using the ion current detection type gas amplification phenomenon will be described with reference to FIGS. 7 (a) to 7 (e). In this example, in the detector that detects the ions obtained as a result of gas amplification, an example of the effect of suppressing the image flow by applying a voltage to the sample is shown. As the sample 114, the copper mesh 201 and the copper ring 202 are used in the same manner as in FIGS. 2A to 2E, and the sample 114 is observed with a scanning electron microscope. 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 in which the copper mesh 201 and the copper ring 202 are observed when the voltage applied to the sample is 0 V. be. FIG. 7B is a schematic view of FIG. 7A for explaining an example of the image flow of the image of the scanning electron microscope. In FIG. 7A, for the reason described above, the image flow portion 203 shown in FIG. 7B can be seen in the copper ring 202 portion. FIG. 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 scanning speed of the primary electron beam 104. Therefore, the copper mesh 201 This is because the gap portion 204 between the spaces flows from the left side to the right side of the image in the scanning direction to display the image flow portion 203.

FIG. 7 (c) is a scanning electron microscope image when a positive voltage is applied to the sample in the present invention, and the scanning speed is 1.56 microseconds / pixel under the same conditions as the image acquisition of FIG. 7 (a). , It is a scanning electron microscope image when a positive voltage of + 10V is applied to a sample. Further, FIG. 7 (d) 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. 7 (a) is 1.56 microseconds /. It is a scanning electron microscope image when a negative voltage of -10V is applied to a sample in pixels. FIG. 7 (e) is a schematic view of FIGS. 7 (c) and 7 (d) for explaining the effect of suppressing the image flow of the image of the scanning electron microscope. The image flow can be suppressed in both the scanning electron microscope images of FIGS. 7 (c) and 7 (d), and the image flow portion 203 shown in FIG. 7 (b) disappears in the copper ring 202 portion, and the copper mesh is eliminated. It has become possible to confirm the clear structure of the above and the foreign matter 701 on the copper mesh shown in FIG. 7 (e). Further, the effect of suppressing the image flow can be obtained regardless of the positive or negative of the voltage applied to the sample.

In Example 1, the effect of suppressing the image flow by applying a voltage to the sample 114 was described. However, by applying a voltage to the sample 114 to suppress the image flow, the SEM image may become dark and the S / N of the image may deteriorate. It is considered that the image flow can be suppressed by applying a voltage to the sample 114, but 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 scanning type is changed according to the case of searching the field of view, adjusting the focus, and 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.

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 searching a field, a low-speed scan button 802 used for confirming an image and fine adjustment of focus, a field limiting scan button 803 used for adjusting focus, and an image display unit. 804, a focus adjustment slider 805 for adjusting the focus of the primary electron beam 104, a non-point adjustment slider 806 for adjusting the non-point of the primary electron beam 104, and the like are provided, and the user can perform various scanning conditions of the primary electron beam 104. It is possible to display the image acquired by the scanning electron microscope while switching between.

When observing using a detector that uses the gas amplification phenomenon, image flow occurs during observation in a high-speed scan in which 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, no image flow occurs in a low-speed scan in which the scanning time of the primary electron beam 104 per pixel is longer than the response speed of the gas amplification phenomenon. That is, it is sufficient that the image flow can be suppressed only during high-speed scanning. On the other hand, as described above, by applying a voltage to the sample 114 in order to suppress the image flow, the signal due to gas amplification becomes small and the S / N of the image may deteriorate. Therefore, by applying a voltage to the sample 114 only during the high-speed scan and controlling so that the voltage is not applied to the sample 114 during the low-speed scan, the S / N is not impaired during the low-speed scan, and the image flow during the high-speed scan. Can be suppressed.

Further, since the magnitude of the image flow suppression effect changes depending on 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. Image flow can be suppressed by applying a voltage closer to the ground than the voltage applied to the sample 114 during the high-speed scan to the sample 114 during the low-speed scan.

Further, when the voltage applied to the sample 114 is changed, the state of the gas amplification phenomenon changes and the brightness of the image also changes. Therefore, in order to compensate for the change in brightness, the voltage of the electric field supply electrode 132 is scanned by the primary electron beam 104. The process of changing the image according to the speed or automatically adjusting the brightness of the image may be executed at the same time as 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: Scanning electron microscope system ,: 101: Filament, 102: Wenert, 103: Electrode, 104: Primary electron beam, 105: Upper gun alignment coil, 106: Lower gun alignment coil, 107: First focusing lens, 108: First Two-condenser lens, 109: Objective aperture, 110: Aligner, 111: Upper deflection coil, 112: Lower deflection coil, 113: Objective lens, 114: Sample, 115: Sample stand, 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 stand, 128: computer, 129: display device, 130: storage means, 131: input means, 132: electric field supply electrode, 201: copper mesh, 202: Copper ring, 203: image flow part, 204: gap part, 301: line profile acquisition part, 701: foreign matter, 801: high-speed scan button, 802: low-speed scan button, 803: field-limited scan button, 804: image display part, 805: Focus adjustment slider, 806: Non-point adjustment slider

Claims (8)

An irradiation optical system that irradiates a sample with an electron beam,
With the sample table
An electric field supply electrode that supplies an electric field that acts on the electrons generated by the irradiation of the electron beam, and
A deflection coil for changing the scanning speed of the electron beam and a power supply for applying a voltage to the sample are provided.
A first voltage is applied to the sample to image at a first scanning speed, and a second voltage closer to the ground than the first voltage is applied to the sample to be slower than the first scanning speed. A scanning electron microscope characterized by imaging at a second scanning speed. In the scanning electron microscope according to claim 1,
A scanning electron microscope characterized in that the electrons generated by irradiation of the electron beam are secondary electrons. In the scanning electron microscope according to claim 1,
A scanning electron microscope characterized in that the voltage of the electric field supply electrode is controlled when the scanning speed of the electron beam is changed. In the scanning electron microscope according to claim 1,
A scanning electron microscope characterized in that when the scanning speed of the electron beam is changed, the brightness of the image to be captured is automatically adjusted for imaging. Place the sample on the sample table and place it on the sample table.
Irradiate the sample with an electron beam and
The electric field acting on the electrons generated by the irradiation of the electron beam is supplied by the electric field supply electrode, and the electric field is supplied by the 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 than the first voltage is applied to the sample to be slower than the first scanning speed. A method for imaging a scanning electron microscope, which comprises changing the scanning speed to a second scanning speed and taking an image. In the imaging method of the scanning electron microscope according to claim 5,
A method for imaging a scanning electron microscope, wherein the electrons generated by irradiation of the electron beam are secondary electrons. In the imaging method of the scanning electron microscope according to claim 5,
A method for imaging a scanning electron microscope, which comprises controlling the voltage of the electric field supply electrode when the scanning speed of the electron beam is changed. In the imaging method of the scanning electron microscope according to claim 5,
An imaging method of a scanning electron microscope, which automatically adjusts the brightness of an image to be imaged when the scanning speed of the electron beam is changed.

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