JP2005191017A - Scanning electron microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable high precision and high resolving power observation in a short time without expertise even toward an easily electrified testpiece by having a function to sense and report an electrification phenomenon causing precision deterioration or resolving power lowering and by simplifying a countermeasure against electrification. <P>SOLUTION: A scanning electron microscope senses the electrification phenomenon with a surface potential observing measure of an observed sphere of the testpiece or with a monitoring measure of the image change by that, and has a display measure of that effect. The countermeasure against electrification is actuated on the basis of the observed effect of the surface potential, the monitored effect of the image, or sorting items of those effects. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a scanning electron microscope, and more particularly to a scanning electron microscope suitable for observation and measurement of a sample that is easily charged in an apparatus in which an electron beam is accelerated for a semiconductor.

  A conventional scanning electron microscope (SEM) accelerates an electron beam emitted from an electron source, forms a thin electron beam with an electron lens, and scans this as a primary electron beam on a sample using a scanning deflector. An image was obtained by detecting secondary electrons or reflected electrons. For semiconductor inspection, for example, as disclosed in Japanese Patent Application Laid-Open No. 09-171791, high resolution is maintained by applying a potential to the inspection sample and reducing the energy of the primary electron beam incident on the sample to a low acceleration of about 1 kV. However, the defects were reduced and the charge of the insulator was reduced.

JP-A-9-171791

In a conventional low-acceleration SEM, in a sample having an insulator film or the like on the surface, even if it is reduced, a certain amount of charge is accumulated due to electron beam irradiation, and the surface potential changes.
In this SEM, since the energy of the primary electron beam is small, the measurement dimensional accuracy deteriorates even with a slight potential change. In addition, there is a problem that observation and measurement with high resolution becomes difficult due to drift and contrast reduction.

  As a measure against charging, for example, as disclosed in Japanese Patent Laid-Open No. 5-151924, as a means for detecting positive charging, a region observed immediately before when observed at a high magnification after observing at a high magnification is A method has been devised to check and inform that it is darker than the surrounding area.

  Further, as an empirical method for observing a charged sample, there is a method called pre-dose as disclosed in JP-A-5-151927. In this method, an electron beam is irradiated for a certain period of time to a region wider than the region that is originally desired to be observed once at a low magnification, and then returned to a high magnification for observation.

  In these examples, there is a problem that the operation time becomes long because the operator repeats trial and error and performs various studies each time. In addition, since a high level of skill is required for the operation, there is a problem that it is difficult to carry out in actual development and production.

  A first object of the present invention is to provide a scanning electron microscope having a function of sensing and notifying a charging phenomenon that causes deterioration in accuracy and resolution.

  A second object of the present invention is to provide a scanning electron microscope that performs charging countermeasures based on the information thus obtained, and enables observation and measurement with high accuracy and high resolution.

  A third object of the present invention is to provide a scanning electron microscope capable of performing observation and measurement with high accuracy and high resolution without requiring skill even in a sample that is easily charged.

  In order to achieve the first object, the scanning electron microscope according to the present invention senses a charging phenomenon by means of surface potential observation means in the observation region of the sample or monitoring means for image change thereby, and further displays the result. Have means.

The surface potential observation means may be an energy analysis means for secondary electrons, a means for observing a deviation in the focal position of the sample height sensor and the electron beam due to the light beam, or a means for changing the potential of the sample.
The image change monitoring means may be a means for digitizing the contrast of the image every time, a means for providing an image cache memory and comparing the changes at each moment side by side, or monitoring the change in the brightness of the image. It may be a means to do.

  The result display means is a means for displaying the observation result of the surface potential, the monitor result of the image change, or the classification item of these results, and an image display device or a dedicated indicator may be used. .

In order to achieve the second object, there is provided means for taking measures against charging based on the observation result of the surface potential, the monitoring result of the change of the image, or the classification item of these results.
The countermeasure against charging is the function to irradiate the electron beam for a predetermined time, the means to switch the sweep of the electron beam, the function to irradiate the electron beam for a predetermined time by reducing the magnification, the function to change the acceleration voltage of the electron beam, and the emission current from the electron source. It is a function to change or a means for neutralizing the surface charge.

  In order to achieve the third object, a charging phenomenon sensing means, a result display means, a charging countermeasure means, and a switch for operating these functions are provided.

  By using the present invention, it is possible to provide a scanning electron microscope having a function of sensing and notifying a charging phenomenon that causes deterioration in accuracy and resolution. In addition, it is possible to provide a scanning electron microscope that takes measures against charging and enables measurement with high accuracy and high resolution. In addition, it is possible to provide a scanning electron microscope that can perform observation and measurement with high accuracy and high resolution in a short time without requiring skill even with a sample that is easily charged.

(Example 1)
In this embodiment, a structure formed on a semiconductor substrate is used to check a photoresist pattern for a hole for making an electrical contact with an electrode under an insulator film, a so-called contact hole. A description will be given based on an example of observing a photoresist on SiO ₂ as a sample.

  FIG. 1 shows an example of a display screen of an embodiment of the scanning electron microscope of the present invention. The apparatus configuration is as shown in FIG.

  In the apparatus shown in FIG. 10, 401 is an electron source, 403 is a lens barrel unit serving as an examination room, 404 is an electron optical system, 405 is an image processing unit, 406 is a control unit, 407 is a secondary electron detection unit, and 408 is a sample chamber. 409, substrate to be inspected, 411 anode, 412 condenser lens, 413 blanking deflector, 414 aperture, 415 scanning deflector, 416 objective lens, 418 E × B deflector, 419 electron beam , 420 is a secondary electron detector, 430 is a sample stage, 431 is an XY stage, 432 is a correction control circuit, 433 is a stage controller, 434 is a substrate height measuring device, 435 is a retarding power supply, 441 is a scanning A deflector power source, 442 is an objective lens power source, and 451 is a secondary electron.

  In the step of forming the contact hole, (1) a step of forming a photoresist on the insulator film and (2) a step of etching the insulating film using the photoresist as a mask determine the processing accuracy. The diameter of the contact hole is as small as about 1 μm or less, and in each process, an electron microscope as shown in FIG. 10 is used in order to confirm processing accuracy and whether or not the hole is open.

In the sample of (1) above, when the hole is observed at an acceleration voltage of 1 kV, the secondary electron yield of the underlying SiO ₂ is about 1 or more and the photoresist is about 2 or more. a lot. As a result, the surface begins to be positively charged simultaneously with the start of electron beam irradiation.

  As shown in FIG. 6A, the charging speed of the photoresist is about 10 times or more faster and reaches 100 V or more in a few minutes. The image observed with an electron microscope is exclusively secondary electrons with low energy. For this reason, as shown in FIG. 3, as the photoresist is charged, electrons emitted from the inside of the hole are bent, and are difficult to detect. As a result, in the conventional SEM, as schematically shown in FIG. 2, the contrast is lowered at a high magnification, the dimensional accuracy is deteriorated, or image observation is impossible.

  At this time, as shown in FIG. 7, since the contrast of the image from the start of irradiation with the electron beam changes depending on the charge amount and time, it is detected based on this result that charging is performed. Thus, by displaying the result on a part of the screen, the operator can be informed of the charging state.

  Specifically, as a detection method, as shown in FIG. 13, among the brightness distributions of the pixels of the nth frame, the average value <S> n and the deviation σn are used as the brightness of the nth frame. Then, it is digitized as a contrast and the change between frames is known as shown in FIG. Usually, since there is a pattern in the observation area, it can be detected by contrast change.

  For a sample with low image contrast or a sample with insufficient pattern steps and sufficient contrast, the brightness can be viewed. Alternatively, the secondary electron intensity of each image may be digitized and the change in this value may be observed. When the contrast and brightness of each image are automatically corrected, the charging phenomenon can be detected more directly by using the secondary electron intensity and the reflected electron intensity. In addition, the graphs of FIGS. 13B and 13C may be displayed as an image or output as a file. In this case, more detailed information on the sample can be obtained.

  In ordinary scanning electron microscopes, all secondary electron signals with a wide dynamic range are not AD converted. 8-bit AD conversion is performed by limiting the intensity range so that the contrast and brightness fall within a certain range. A 256-level brightness signal is obtained through the instrument. Therefore, if more gradations are recorded, more information can be obtained from the image signal, which is advantageous for detecting the charging phenomenon. In practice, it is effective to use a 12-bit AD converter. With this image signal, it is possible to capture a signal change in a region that has been cut off in the past because it is too bright or too dark. Further, even for a sample with a low overall contrast, the change in the total amount of secondary electrons can be measured from the image signal.

  As described above, when a 12-bit AD converter is used, there is an advantage that a large amount of information can be recorded or processed by an image signal. Note that the gradation that can be handled depends on the size of the memory and the processing capacity of the computer, and these capabilities are increasing year by year. Therefore, if the gradation is increased to 16 bits, 24 bits, 32 bits, etc., the effect becomes even more effective. There is.

  Here, the signal processing for detecting the charging phenomenon is intended for the entire image, but it is not always necessary to use only the signal in a desired region. As an actual operation, for example, as shown in FIG. 14, an observation region may be designated on the observation image with an arrow cursor. The cursor may be moved by using a dedicated switch, mouse, trackball, keyboard or the like alone or in combination of two or more. The same effect can be obtained by placing a touch switch on the screen and specifying with a pen or a finger. Further, the designated area may be outside the observation area. Also in this case, it is useful to display a graph as shown in FIGS. 13B and 13C in the designated area or output it as a file.

  After the charge detected by the above method is displayed on the screen, the magnification is further reduced automatically from 1/5 to 1/20, so that a wider area is irradiated with an electron beam and the irradiation area is temporarily The contact hole can be observed with high resolution by performing so-called pre-dose treatment that imparts conductivity to the electrode to reduce the charge amount. The effect of the pre-dose treatment is based on the principle described below.

Since normal insulators SiO ₂ and Si-N are amorphous or microcrystalline, there is no conduction band or valence band across the band gap handled by a single crystal semiconductor, but there is a mobility gap. It exists and behaves like a wide gap semiconductor. Recently, it is also treated as a band gap without being distinguished from a single crystal.

The value is about 5 to 9 eV for SiO ₂ and about 5 eV for Si—N. When irradiated with an electron beam, ultraviolet light, soft X-ray or the like having an energy close to or greater than the band gap energy, the combined electrons are excited and become easy to move around. In addition, the hole from which the electron has been removed becomes a carrier that carries a positive charge as a hole. As a result, the electrical conductivity increases during irradiation. The electrical conductivity σ at this time is expressed by the following formula 1.

[Equation 1]
σ = q (μn ・ N + μp ・ P) (1)
Here, q is the charge of electrons, μn and μp are the mobility of electrons and holes, respectively, and N and P are the densities of electrons and holes, respectively.

  An example of this is described in Japanese Journal of Applied Physics, 1995, Volume 34, pages 1376 to 1380.

  In the scanning tunneling microscope (STM), it is difficult to observe an image because an electric current does not flow if there is an insulating silicon oxide film. However, by irradiating this with a high-energy electron beam, electrons and holes are generated in the oxide film to impart conductivity, so that image observation is possible. In this case, since the energy of incident electrons is high (20 kV), an electron beam enters the entire film, and much more electrons and holes are generated than incident electrons due to multiple scattering, so that the conductivity is extremely high. However, when the electron beam irradiation is stopped, the electrons and holes are quickly recombined and disappear, so that the conductivity drops rapidly.

  In low-acceleration SEM, electrons and holes are generated in the vicinity of the surface by electron beam irradiation, some of which recombine and disappear, and some of the electrons are emitted as secondary electrons. As will be described later, when the secondary electron yield is not 1, either electrons or holes remain. Since the periphery is an insulator, the surface charge is accumulated, and even when the electron beam irradiation is stopped, the electrical conductivity represented by the above equation remains in the region where the surface charge is accumulated.

  Based on the above results, pre-dose makes it possible to diffuse the charge accumulated up to the time of electron irradiation to a wider area and increase the electrical conductivity of the surface for a while after electron irradiation, and increase the magnification for observation. Thus, the effect of reducing the accumulation of charge during the operation can be obtained. Further, during pre-dosing, it is not necessary to display an image in particular, and an electron beam may be irradiated to an area wider than the observation area.

In addition, although the inorganic solid was described here as an example, even in the case of an organic substance such as a resist, since the organic molecules gather and the neighboring molecules are spatially close to each other, each molecular orbital overlaps, Since the energy level expands, the pre-dose is effective because it behaves in the same manner as SiO ₂ or Si-N. In this case, since there are many levels that do not contribute to electrical conduction and spatially bind carriers, it is necessary to accumulate a certain amount of charges.

In addition to the above, to increase the surface conductivity and disperse the charge, the same effect can be obtained by irradiating a wider area with an electron beam at a time other than the time when the electron beam is swept in a desired area. It is done. For example, a sweep of a wide area may be inserted between the line sweeps of a desired area, or an electron beam may be irradiated to a wide area after the sweep of one screen is completed.
In these cases, as the second display image, a secondary electron image when the wide area is irradiated with an electron beam may be displayed. In this case, the second image display includes the observation area of the first image, and when it is charged, a contrast change due to charging appears. There are advantages.

In addition to the probe electron beam irradiation of the quotation, energy rays such as electron beam, ion beam, ultraviolet ray, soft X-ray from other electron sources can increase the conductivity on the sample surface. The same effect as above can be obtained. These energy rays can be irradiated even during the electron beam sweep of a desired region.
If the amount of charge is large and sufficient observation is not possible even after pre-dose, the effect of charge amount and charge can be alleviated by changing the acceleration voltage of the electron beam.

  In the case of a sample whose dimensions are a problem as shown in FIG. Although image observation is possible even when charged, the trajectory of the electron beam is disturbed, so that the Wv accuracy differs by 10 to 20 nm compared to the Wh accuracy. In this case, Wv can be accurately measured by performing raster rotation by rotating the sweep direction by 90 °.

Here, countermeasures against charging are automatically taken, but they may be taken manually if the operator is skilled. In this case, a cancel switch for automatic processing such as a cancel button is provided.
Here, one example of detection of a charging phenomenon and several examples of countermeasures against charging have been used. However, since the charging phenomenon generally has the following principle, there are other countermeasure methods. Examples thereof will be described later.
The charging phenomenon is expressed by the following formula 2.

[Equation 2]
dEs / dt = (1 / C) * (− J + YJ−L) (2)
Here, Es is the surface potential, C is the capacitance, J is the incident electron beam current, Y is the secondary electron yield, and L is the leakage current.

  The above C and Y are different depending on the material and its shape. In particular, Y varies depending on the energy E of the incident electron beam and has a distribution as shown in FIG. In normal SEM observation, the energy of the incident electron beam is about 800 V to several kV, and the slope is a negative region. The E2 point of Y = 1 is an equilibrium point and differs depending on the material. The incident electron beam is negatively charged at point A where the energy is higher than this, and conversely charged positively at point B where the energy is low, both of which change in potential until Es becomes E−E2.

Therefore, when the acceleration voltage is 1 kV, the potential varies depending on the material as shown in FIG. In addition, when the SiO ₂ film is thick, C decreases, so that the potential of the SiO ₂ film increases as shown in FIG. 6B. As a result, the amount of charge changes because the potential of the resist in the vicinity of the charged region is also raised. When the acceleration voltage is as high as 2 kV, the SiO ₂ film is negatively charged because Y is smaller than 1 as shown in FIG. At this time, the charged potential of the resist also decreases. As the voltage is further increased, the resist charge goes from 0 to negative. In this way, the charge amount varies strongly depending on the material and the acceleration voltage of the electron beam.

  Contrast appears in the observed image because there are two or more types of materials, or there are steps. As shown in FIG. 7, this also changes due to charging. This is because of changes in surface potential, changes in secondary electron orbits, and the like. Therefore, the degree of charging can be known from this change.

In order to observe this change, as described above, the contrast may be digitized for each scan, and the change in this value may be observed. However, as shown in FIG. It is also effective to store memory and store images at each scan at high speed for comparison. In this case, it is difficult to store all the images because the memory capacity is limited. Therefore, it is effective to allow the operator to set the image number n to be left in the memory. For example, in the case of samples with many insulators, it is effective to keep the first 10 frames of the measurement because it is a region where the amount of change is large, always store the latest image in the remaining memory, and erase the overflowed image in chronological order. It is. If a sufficient contrast image is obtained only in the first few frames, it can be used for dimension measurement, shape analysis, and the like.
By obtaining information on the charge amount by this method and displaying it on the screen, it is possible to know the next measure or the accuracy of the measurement value.

As a countermeasure against charging, the following steps are provided.
If the amount of charge is large, the contrast decreases with time. What is necessary is to measure in a stable region where the change has stopped to some extent. As shown in FIG. 7 and FIG. 8, this relationship may be observed at the time after the change region determined for each case.
Here, FIG. 8 is a graph conceptually showing the relationship between the electron dose to the sample and the irradiation time. If the observation changes even more vigorously and observation is difficult, the charge is dispersed by irradiating a wide area with an electron beam and the magnification is increased again for observation. Further, when the change is severe and the pattern cannot be seen, the charge amount can be reduced by changing the acceleration voltage. It is also effective to extend the charging time by reducing the emission current.

  In addition, when the charge amount is large, the surface charge is dispersed or neutralized and reduced by irradiating ultraviolet rays or soft X-rays, or irradiating ultraviolet rays or X-rays in an ion generator or gas. Is effective.

From the above, it is effective to classify the rank of charge as shown in FIG. 9 according to the charge amount and the acceleration voltage of the electron beam, and to select the charge countermeasure processing method accordingly.
Here, the classification is from A to E, but the classification may be increased or decreased depending on the required accuracy and the type of sample.

  In this embodiment, the charge amount is evaluated from the image, but means for measuring the actual potential of the sample surface may be provided. In this case, evaluation with higher accuracy becomes possible.

  As a means for directly measuring the potential, a method of measuring the energy of secondary electrons is effective. As shown in FIG. 11, when the potential of the secondary electron detector or the electrode around it is changed, electrons in a specific region can be captured, so that the rough energy of the secondary electrons can be known. . The energy when secondary electrons escape from the sample is often as low as about 10 V or less, so this energy is almost comparable to the surface potential. For practical purposes, it is sufficient to be able to distinguish between the three areas at + 100V and -100V. In addition to this, as a method for measuring the energy of the secondary electrons, a dedicated energy analyzer may be used, and in that case, more accurate potential measurement can be performed.

Further, a deviation between the result of measuring the height of the sample surface by light reflection and the result of autofocusing by the electron optical system may be used, or the voltage of the sample may be changed.
These make use of the fact that the energy of the electron beam applied to the sample surface deviates greatly from the design value when the surface becomes a high voltage ± 100 V or more due to charging.

Explanatory drawing which shows an example of the observation image in Example 1 of this invention. Explanatory drawing of a prior art. Sectional drawing of the sample in Example 1 of this invention. FIG. 2 is an explanatory diagram of the principle of the present invention. FIG. 2 is an explanatory diagram of the principle of the present invention. The graph which shows the electric potential change by the material of the sample surface in Example 1 of this invention. 3 is a graph showing a change in contrast of an observation image in Example 1 of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. Explanatory drawing which shows the response | compatibility of the charge rank and coping method in Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the structure of the scanning electron microscope of Example 1 of this invention. Explanatory drawing which shows the structure and function of the secondary electron detection part in Example 1 of this invention. The block diagram of the image signal processing part which shows the modification of Example 1 of this invention. Explanatory drawing of the charge detection process of Example 1 of this invention. Explanatory drawing of the other example of the charge detection process of Example 1 of this invention.

Explanation of symbols

401 ... Electron source, 403 ... Inspection room, 404 ... Electronic optical system, 405 ... Image processing unit, 406 ... Control unit, 407 ... Secondary electron detection unit, 408 ... Sample chamber, 409 ... Substrate to be inspected, 411 ... Anode, 412 ... condenser lens, 413 ... blanking deflector, 414 ... aperture, 415 ... scanning deflector, 416 ... objective lens, 418 ... ExB deflector, 419 ... electron beam, 420 ... secondary electron detector, 430 ... Sample stage, 431 ... XY stage, 432 ... correction control circuit, 433 ... stage controller, 434 ... substrate height measuring instrument, 435 ... retarding power supply, 441 ... scanning deflector, 442 ... objective lens power supply, 451 ... Secondary electrons.

Claims (19)

  A scanning electron microscope characterized by having means for detecting a charging phenomenon on the surface of the sample and a display means for the result on or near the observation image   2. The scanning electron microscope according to claim 1, wherein the means for sensing the charging phenomenon is a surface potential observation means for the observation region of the sample or at least one signal of a display image, a secondary electron image, and a reflection electron image. A scanning electron microscope characterized by being a monitoring means for changes in the above.   3. The scanning electron microscope according to claim 2, wherein the means for sensing the charging phenomenon is an energy analysis means for secondary electrons.   3. The scanning electron microscope according to claim 2, wherein the means for sensing the charging phenomenon is a means for observing a deviation in a focal position of the electron beam height sensor from the specimen by the light beam. microscope.   3. The scanning electron microscope according to claim 2, wherein the means for sensing the charging phenomenon is a means for detecting a change in the potential of the sample.   3. The scanning electron microscope according to claim 2, wherein the means for sensing the charging phenomenon is means for digitizing at least one of contrast or brightness of an image every time. microscope.   3. The scanning electron microscope according to claim 2, wherein the means for sensing the charging phenomenon is a means for providing a cache memory of images and comparing changes at each moment side by side.   3. The scanning electron microscope according to claim 2, wherein the means for sensing the charging phenomenon monitors at least one value of contrast or brightness of at least one signal of a secondary electron image and a reflected electron image. A scanning electron microscope characterized by comprising:   A scanning electron microscope having a means for sensing a charging phenomenon on the sample surface and a display means for displaying the result, wherein the means for sensing the charging phenomenon is a surface potential observation means in the observation region of the sample or a display image thereby. It is a monitoring means for a change in at least one signal of the secondary electron image and the reflected electron image. Specifically, it is an energy analysis means for secondary electrons, or a sample height sensor using a light beam and the focus of the electron beam. Means for observing positional deviation, means for changing the potential of the sample, means for digitizing at least one of the contrast or brightness of the image every time, or a cache memory for the image, and changes at each moment Of contrast or brightness of at least one signal of secondary electron image or reflected electron image A means for monitoring at least one numerical value, the charging phenomenon detection result display means for displaying the observation result of the surface potential or the monitoring result of the change of the image and the classification items of the result, A scanning electron microscope characterized by displaying on a display device or a dedicated indicator.   The scanning electron microscope according to any one of claims 1 to 9, comprising means for taking measures against charging based on the observation result of the surface potential, the monitoring result of the change in the image, or the classification item of these results. A scanning electron microscope comprising:   The scanning electron microscope according to claim 10, wherein the means for taking measures against charging is a means for irradiating an electron beam for a predetermined time, a means for switching sweeping of an electron beam, a means for irradiating an electron beam for a predetermined time at a reduced magnification, A scanning electron microscope comprising at least one of means for changing an acceleration voltage of an electron beam, means for changing an emission current from an electron source, and means for neutralizing a surface charge.   12. The scanning electron microscope according to claim 10 or 11, wherein all, or two, or one function of a charging phenomenon detecting means, a display means for the result, and a means for taking measures against charging are used. A scanning electron microscope comprising a switch.   9. The scanning electron microscope according to claim 1, wherein a gradation per pixel of the image is 12 bits or more.   9. The scanning electron microscope according to claim 1, wherein the sample surface area observed by the means for sensing the charging phenomenon is designated as a desired area different from the display image. A scanning electron microscope.   15. The scanning electron microscope according to claim 14, wherein the sample surface area for observing the charging phenomenon is in a display image, and a desired area is designated while displaying the area in the image. A scanning electron microscope.   12. The scanning electron microscope according to claim 10 or 11, wherein, as a means for performing the countermeasure against charging, at least one of energy beams such as an electron beam, an ion beam, an ultraviolet ray, and a soft X-ray is applied to a region wider than a desired observation region. A scanning electron microscope comprising means for irradiating one.   The scanning electron microscope according to claim 16, wherein the means for taking measures against charging is in an area wider than the observation area during the electron beam sweep for observing a desired area or outside the sweep time and during sample observation. A scanning electron microscope comprising means for irradiating at least one of energy beams such as an electron beam, an ion beam, an ultraviolet ray, and a soft X-ray.   17. The scanning electron microscope according to claim 16, wherein the means for taking measures against charging is wider than the observation region for the observation electron beam outside the electron beam sweep time for observation of a desired region and during sample observation. A scanning electron microscope characterized by being means for irradiating an area. The scanning electron microscope according to any one of claims 6, 7, 8, 14, and 15, wherein a display image, a secondary electron, or a reflected electron that is quantified as one of means for sensing the charging phenomenon. A scanning electron microscope characterized by displaying a time change of at least one of contrast and brightness of at least one signal.

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