KR20020032283A - Method of capturing scanning electron microscopic images and apparatus of scanning electron microscope used in the same - Google Patents

Abstract

PURPOSE: A method of attaining a scanning electron microscope picture is provided to restrain a pattern shift and to easily adjust the focus by deliberately supplying electric charges on a surface of a sample. CONSTITUTION: Electric charges are implanted on a sample(100) made of a substrate(110) and a chrome pattern(150) by an electric charge generator(500) such as an ionizer. An electron beam column part(300) scans the resultant structure by a first electron beam in order to extract second electrons. The emitted second electrons are captured by a second electron detection part(410). Then, the captured second electrons are transformed to signals by an amplifier(430) and a filter part(450). A picture of the surface of the sample(100) is formed by a picture display part(470).

Description

Method of capturing scanning electron microscopic images and apparatus of scanning electron microscope used in the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope (SEM), and more particularly, to a method of obtaining a surface SEM image of a photo mask used in the manufacture of a semiconductor device, and a SEM apparatus used therein.

SEM images are used for the analysis required to fabricate semiconductor devices, for example for analyzing the surface of a sample. For example, in order to measure CD (Critical Dimension) etc. of the pattern formed in the sample surface, the method of obtaining the SEM image of the sample surface and measuring the CD of the pattern shown in such a SEM image is used.

As known, the SEM apparatus is used to obtain a picture of the sample surface by irradiating a primary electron beam to the sample surface, detecting a secondary electron signal emitted from the sample surface. As such, since the SEM device uses an electron beam, the SEM charge is greatly influenced by the electric charge level of the sample surface.

In a laboratory environment, in order to exclude the influence of the potential level of the sample surface, a method of forming a ground by gold coating of the sample surface has been proposed. However, in the case of manufacturing a semiconductor device, it is difficult to introduce the gold coating as described above in the sample to obtain the SEM image, and thus it is impossible to substantially ground. In addition, a method of performing SEM imaging by simply grounding a sample using a ground pin or the like has been proposed. However, when the surface of the sample is made of a non-conductor or a conductor separated from the non-conductor, The grounding effect cannot be exerted.

For example, in the case of a photo mask used for manufacturing a semiconductor device, since a light shielding film pattern formed on a quartz substrate, for example, a chromium pattern is independently separated or insulated by a quartz substrate, there is no method of directly grounding it. . Therefore, it is very difficult to obtain an SEM image of this photo mask surface. For example, defects such as a pattern shift phenomenon that may make it difficult to attain initial focus, distortion, or a shifted image at a desired position during SEM imaging may occur.

An object of the present invention is to provide a method for obtaining a scanning electron microscope image of a surface of a sample made of a nonconductor or a conductor separated by a nonconductor.

Another object of the present invention is to provide a scanning electron microscope device for use in the method for obtaining the scanning electron microscope image.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the scanning electron microscope apparatus shown in order to demonstrate the method of obtaining the scanning electron microscope image which concerns on the Example of this invention.

FIG. 2 is a view schematically illustrating a state in which a photo mask applied in an embodiment of the present invention is mounted on a specimen holder.

FIG. 3 is a diagram schematically illustrating an ionizer employed in an embodiment of the present invention.

4 and 5 are cross-sectional views schematically illustrating diffraction phenomena of incident electrons due to charge distribution non-uniformity of a sample surface as compared with an embodiment of the present invention.

Figure 6 is a schematic cross-sectional view for explaining the purpose of charging the sample surface in accordance with an embodiment of the present invention.

7 is a SEM photograph taken after the charge is intentionally charged on the surface of the photo mask according to the embodiment of the present invention.

FIG. 8 is a SEM photograph of a surface of a simple grounded photo mask prepared in accordance with an embodiment of the present invention. FIG.

FIG. 9 is a view illustrating a time and flow direction in which a pattern shift phenomenon measured at set nine points of a surface of a simple grounded photo mask is maintained compared to an embodiment of the present invention.

FIG. 10 is a view illustrating a time and flow direction in which a pattern shift phenomenon measured at nine set points of a photo mask surface is maintained according to an exemplary embodiment of the present invention.

FIG. 11 is a graph illustrating a result of measuring a critical line width using a SEM photograph of a chromium pattern of 0.92 μm according to an embodiment of the present invention.

12 is a diagram schematically illustrating a state in which a charge generating unit is installed at a loader position of an SEM device according to an embodiment of the present invention.

FIG. 13 is a view schematically illustrating a state in which a charge generating unit is installed in an auxiliary chamber of an SEM device according to an embodiment of the present invention.

14 is a view schematically illustrating a state in which a photo mask and a specimen holder are insulated according to an embodiment of the present invention.

15 is a view showing a measuring point for measuring the effect of the photomask surface in the non-grounding state according to the embodiment of the present invention.

16 to 19 are SEM images obtained at the points shown in FIG. 15 when the ground pin is used.

20 to 23 are SEM images obtained at the points shown in FIG. 15 when the ground pin and the photo mask surface are insulated according to an embodiment of the present invention.

<Brief description of the major symbols in the drawings>

100: sample, 100 ': photo mask,

110: substrate, 150: chrome pattern,

200: specimen holder, 500: charge generating portion,

550: charge level.

One aspect of the present invention for achieving the above technical problem, one aspect of the present invention for achieving the above technical problem is, after intentionally charging a charge on the surface of the sample, the primary surface of the charged sample A scanning electron microscope image is obtained which obtains an image based on a signal of secondary electrons generated by scanning with an electron beam. The sample may have a surface made of a conductor separated by a non-conductor, for example, a photo mask.

The intentional charging of the charge may be performed by a method of charging the surface of the sample by providing ions to the surface of the sample using an ionizer. Alternatively, the intentional charging of the charge may be performed by providing electrons generated from an electron gun to the surface of the sample to accumulate electrons on the surface of the sample. Preferably, the sample surface is not electrically grounded in the intentionally charging of the charge.

Charging the surface of the sample increases the uniformity of the charge distribution on the surface of the sample. Thus, when starting a scan, diffraction can be prevented as the primary electron beam approaches the surface of the sample. Thus, primary electron beams can be fixed at the intended spot. That is, the focus of the primary electron beam may be good.

Another aspect of the present invention for achieving the above technical problem is a chamber, an electron beam portion for scanning the beam across the surface of the specimen introduced into the chamber and mounted in the chamber to generate a single-character electron beam, the chamber A secondary electron detector that detects secondary electrons introduced into and emitted from the sample to generate a signal representative of the surface of the target from which the secondary electrons are emitted; and a secondary electron detector connected to the secondary electron detector to convert the signal into an image A scan for obtaining an image of a sample including an image photographing unit including a processing unit for changing, and a sample processing unit including a charge generating unit connected to the image photographing unit and generating an electrical charge and providing the surface of the sample Provided is an electron microscope device. The sample processing unit may include an ionizer or an electron gun that provides ions to the surface of the sample. At this time, it is preferable to further include a specimen holder used to mount the specimen and the specimen holder is electrically insulated from the specimen.

According to the present invention, it is possible to suppress initial focus failure and pattern shift phenomenon during SEM imaging, thereby obtaining a stable SEM image in a short time.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and the like of the elements in the drawings are exaggerated to emphasize a more clear description, and the elements denoted by the same reference numerals in the drawings means the same elements.

Referring to FIG. 1, in the embodiment of the present invention, before the SEM imaging of the surface of the sample 100, an intentional charging of the surface of the sample 100 is provided by intentionally supplying electric charges to the surface of the sample 100. .

For example, when the photo mask is used as the sample 100, the photo mask is provided with the chrome pattern 150 on the quartz substrate 110. Thus, the surface of the sample 100 is composed of a conductor of the chromium pattern 150 isolated by the quartz substrate 110 and the exposed quartz substrate 110 selectively exposed.

Referring to FIG. 2 along with FIG. 1, the photomask 100 ′ used to manufacture a semiconductor device may be divided into an outer circumferential portion 160 and a pattern portion 130. The pattern portion 130 is generally patterned with a chrome pattern 150 used as a light shielding film pattern, and is substantially a portion transferred onto a wafer by a photographic process.

The outer circumferential portion 160 has a chromium layer deposited for the chromium pattern 150 remaining, and the chromium layer of the outer circumferential portion 160 is separated or isolated by the pattern portion 130 and the separating portion 120. do. The separation part 120 is formed by exposing the quartz substrate 110. That is, the chromium layer of the outer circumferential portion 160 is not electrically connected to the chromium pattern 150 existing in the pattern portion 130. In addition, the chromium pattern 150 is independently separated by the surrounding quartz substrate 110 to be exposed.

When the photomask 100 'is placed on the specimen holder 200 for SEM imaging of the photomask 100', the ground pin 250 holds the photomask 100 '. The ground pin 250 directly contacts the outer circumferential portion 160 to electrically ground it. However, since the pattern portion 130 is electrically insulated by the outer circumference portion 160 and the separating portion 150 and is not contacted by the ground pin 250, the chrome patterns 150 of the pattern portion 130 are substantially As a result, it cannot be electrically grounded.

On the surface of the photo mask 100 ′, there may be charge distributions charged by static electricity or plasma introduced in the foregoing process. Such charge distribution is known to be formed substantially non-uniformly, and such non-uniform charge distribution is known to adversely affect the SEM imaging of the surface of the sample 100.

However, when the conductor and the non-conductor coexist on the surface, such as the photo mask 100 ', the surface of the sample 100, in particular, the pattern portion 130 of the photo mask 100' by the simple ground as described above. It is difficult to remove the charged charge. In addition, since the photo mask 100 'and the like are substantially the sample 100 to be used in the semiconductor device manufacturing process, the surface thereof cannot be coated according to a conventional gold coating method.

Therefore, when the SEM image is taken by irradiating a primary electron beam onto the surface of the photo mask 100 'which is simply grounded, the initial focus is affected by the charge distribution charged on the surface of the photo mask 100'. Becomes difficult. Furthermore, even when a SEM image is obtained, an initially set image flows on a monitor of the image display unit 470 of FIG. 1 and the actual object is moved to obtain another object on the screen, that is, a pattern shift phenomenon. This may occur.

In addition, it is difficult to overcome the noise phenomenon generally occurring at the initial stage of imaging during SEM imaging. As the primary electron beam is initially scanned along the surface of the sample 100, noise caused by unevenness of the initial accumulation of electrons on the surface of the sample 100 is uneven, for example, a phenomenon such as a pattern shift phenomenon. It will be difficult to overcome.

The noise phenomenon or the pattern shift phenomenon may be removed when electrons accumulate on the surface of the sample 100 to some extent at an initial stage, but the time required until the pattern shift phenomenon disappears and stabilizes is measured as several minutes or more. do. This time is a big burden for analyzing the sample using SEM in the semiconductor device manufacturing process. For example, to inspect one photo mask 100 ', an image may need to be acquired at approximately 99 points of the photo mask 100' as necessary. In this case, the initial time required to remove the noise phenomenon or the image defect at each of the points becomes as high as approximately several hours when added up. This is a big burden on the semiconductor device manufacturing process.

In order to overcome this, an embodiment of the present invention intentionally provides charge to the surface of the sample 100 prior to performing the SEM imaging to suggest that the surface of the sample 100 is intentionally charged with a certain electrical polarity. Such intentional providing of charge is performed to remove unevenness or unbalance of the charge level on the surface of the sample 100.

Referring back to FIG. 1, the SEM apparatus for performing the method of obtaining the SEM image presented in the embodiment of the present invention may be roughly divided into an image capturing unit 1000 and a sample processing unit 2000. The image capturing unit 1000 may be configured as a known SEM device. For example, the electron beam column part 300 for irradiating the primary electron beam to the sample 100 and the secondary electron detector 410 for detecting secondary electrons emitted from the surface of the sample 100, An amplifier 430 for amplifying the detected signal, a filter 450 for filtering the amplified signal, and an image display 470 for displaying an image obtained by processing such a signal, for example, a monitor. Including, the image capturing unit 1000 is made.

The sample 100 is applied in an environment to which the primary electron beam is irradiated, for example, in a vacuum chamber (not shown), and a SEM image is obtained by a signal according to secondary electrons emitted by irradiation of the primary electron beam. .

The sample processing unit 2000 is introduced to intentionally provide the charge as shown in the embodiment of the present invention to the surface of the sample 100. Accordingly, the sample processing unit 2000 includes a device capable of generating charge or charge particles. For example, the charge generator 500 is provided. The charge generator 500 may be configured of an ion generator that generates ions, for example, a known ionizer.

Referring to FIG. 3, in the ionizer, an electric field is formed around an emitter electrode 505 in the form of a needle by the high pressure generated from the input power source 501. A ground electrode 503 is introduced around the emitter electrode 505. By the electric field formed around the emitter electrode 505, gas molecules, such as air molecules, around the emitter electrode 505 are ionized to form cations and anions in the form of clouds.

The ionizer is known to have a function of adjusting the amount of charge on the surface of the sample 100. That is, the ionizer may serve to charge the surface of the sample 100 to a constant charge level by sending a cation or anion obtained by discharging to an object, that is, the sample 100. At this time, it is known that the ionizer can perform a function of controlling the polarity and the amount of charge charged on the surface of the sample 100 by controlling the amount of anion or cation sent to the surface of the sample 100, respectively. For example, the ionizer may be used to charge the surface of the sample 100 to an overall balanced charge level, such as a charge level of approximately -10V.

The degree of charge of the surface of the sample 100 using the ionizer can be confirmed through a known electrostatic field meter. It is known that the electrostatic field meter can measure the degree of charge on the surface of the sample 100 in a non-contact manner. The above value of about -10V, etc. is an example of the value measured by such an electrostatic field meter. By the electric potential measurement by such an electrostatic field meter, it is confirmed that the surface of the intentionally charged sample 100 can be charged and balanced as a whole at a constant charge level.

As such, by intentionally charging the surface of the sample 100 to a constant charge level, it is possible to implement a balance of the charge distribution on the surface of the sample 100. Accordingly, it is possible to prevent a phenomenon in which primary electrons or the like incident due to an imbalance or unevenness of the charge distribution on the surface of the sample 100 is diffracted or repulsed.

4 and 5, FIG. 4 shows electrons (e ⁻ ) incident on the surface of the sample 100 when two regions charged at −40 V and −10 V exist on the surface of the sample 100. The phenomenon of diffraction due to uneven charge distribution is described. 5 illustrates that when two regions charged at + 40V and + 10V exist on the surface of the sample 100, the incident electrons e ⁻ are diffracted by a nonuniform charge distribution on the surface of the sample 100. It describes the phenomenon. The diffraction of these primary electrons in SEM imaging naturally affects the focus and the like when obtaining an image.

Referring to FIG. 6, FIG. 6 illustrates a balanced formation of the charge level 550 on the surface of the sample 100 using the charge generator 500 such as an ionizer. In this case, the surface of the sample 100 may be balanced to a uniform charge level 550 throughout, for example, approximately -270V. Therefore, incident electrons (e ⁻ ) are suppressed to be diffracted and may be incident on the right incident path to the surface of the sample 100. The above -270V and the like are examples of values measured by an electrostatic field meter.

In addition, as described above, by intentionally charging an electric charge on the surface of the sample 100 before SEM imaging, an initial noise phenomenon due to the uneven distribution of charges on the surface of the sample 100 according to the accumulation degree of primary electrons at the beginning of SEM imaging. Can be removed. That is, during the first electron irradiation for SEM imaging, since the surface of the sample 100 is already charged with a balanced charge level to a constant value, the initial noise phenomenon or the initial image flow (that is, pattern shift) due to accumulation of the primary electrons ) Phenomenon can be prevented.

As described above, the effect obtained by intentionally providing charge particles to the surface of the sample 100, for example, the photo mask 100 ′ and implementing a balanced charge level on the surface of the sample 100 will be described below.

Referring to FIGS. 7 and 8, FIG. 7 is an SEM photograph taken after forming a balanced charge level on the surface of a photo mask using an ionizer according to an embodiment of the present invention, and FIG. 8 is shown in FIG. 2. As shown, the SEM photograph was taken after the photo mask was grounded to the specimen holder 200. In the case of FIG. 7, the photomask surface was charged to a negative polarity charge level using an ionizer, and approximately -270 V was measured as a result of measuring the degree of charge on the surface of the photomask using an electrostatic field meter. .

In the case of Fig. 7, the phenomenon in which the image flows, that is, the pattern shift phenomenon, was removed approximately 15 seconds after the primary electron beam was turned on to obtain a SEM photograph. However, in FIG. 8, the pattern shift phenomenon was removed after waiting for about 165 seconds after the primary electron beam was turned on to obtain the SEM photograph. Arrows in the figures indicate the pattern shift direction.

This result, as in the embodiment of the present invention by providing a charge or charge particles on the surface of the sample 100, to realize the balance of the charge level on the surface of the sample 100 or to the surface of the sample 100 at a constant charge level It is proved that the image realization defect such as an image flow phenomenon which may occur at the beginning of SEM imaging can be prevented by charging the.

9 and 10, FIG. 9 illustrates the time and flow direction in which the pattern shift phenomenon measured at the set nine points is maintained when SEM photographing the grounded photomask surface as in FIG. 8, and FIG. 10. Shows the time and flow direction in which the pattern shift phenomenon measured at the set nine points is maintained when the charge is intentionally charged to the photomask surface according to the embodiment of the present invention. In the case of FIG. 10, the degree of charging measured by the electrostatic field meter on the surface of the photomask after charge charging was approximately -270V uniformly over the entire pattern portion 130 of the photomask.

According to an embodiment of the present invention, the result of FIG. 10 in which the surface of the photomask is intentionally charged prior to SEM imaging, is compared with the result of FIG. 9 in which the surface of the photomask is not intentionally charged. It proves that very short or no pattern shift occurs.

Referring to FIG. 11, FIG. 11 is a graph illustrating a result of measuring a critical line width (CD) using a SEM photograph of a chromium pattern having a line width of approximately 0.92 μm. As the measurement points, nine points were selected for the entire pattern portion 130 of FIG. 2 as shown in FIGS. 9 and 10.

The graph of 1101 indicates the CD measurement of the chromium pattern measured when no charge was intentionally charged on the surface of the photomask with chromium pattern. The graph of reference numeral 1103 represents the CD measurement of the chromium pattern measured when the charge was intentionally charged to the surface of the photo mask according to the embodiment of the present invention as described above, and the graph of reference numeral 1105 is the preceding two. The difference value between the graphs is shown.

The results shown in FIG. 11 show that the CD of the pattern can be sufficiently measured even through the SEM image obtained using the embodiment of the present invention. As described above, the CD measurement of the pattern can measure not only the CD measurement of the chromium pattern, but also the line width of the quartz substrate exposed by the chromium pattern.

Referring back to FIG. 1, when using an ionizer or the like as the charge generating unit 500 as described above, such a charge generating unit 500 is outside the chamber of the image capturing unit 1000 on which the sample 100 is mounted. Can be introduced. In addition, the charge generator 500 may be installed in connection with the chamber.

Referring to FIG. 12, the ionizer used as the charge generating unit 500 may be installed in a loader 495 connected to the chamber 490 to load the sample 100 into the chamber 490. Can be.

Referring to FIG. 13, the charge generating unit 500 may be installed in the auxiliary chamber 497 connected to the chamber 490 and prepared. As described above, when the auxiliary chamber 497 is provided, an electron gun may be installed inside the auxiliary chamber 497 instead of an ion generator such as an ionizer as the charge generator 500.

In the case of using such an electron gun, when the electron beam generated from the electron gun is irradiated to the surface of the sample 100 on the surface of the sample 100, charges of negative polarity caused by electrons may be accumulated on the surface of the sample 100. Accumulation of electrons can provide an effect similar to intentionally charging the surface of the sample 100 to a constant charge level as described above by providing ions of negative polarity to the surface of the sample 100 using an ionizer. On the other hand, in the case of using the ionizer, the surface of the sample 100 may be charged with a negative polarity, and may be charged with a positive polarity as necessary.

On the other hand, when the sample, for example, the photo mask 100 'is placed on the specimen holder 200 of the SEM equipment, as shown in Figure 2, the photo mask 100' is generally grounded by the ground pin 250 . However, when the charge is intentionally charged to the surface of the photo mask 100 ′ as described above, the portion of the photo mask 100 ′ in contact with the ground pin 250, that is, the outer circumferential portion 160 is grounded. Since the ground is electrically grounded through the pin 250, the electric charges charged on the surface of the outer circumferential portion 160 are grounded to the outside of the photo mask 100 ′ and removed. Therefore, even if the electric charge is intentionally charged on the entire surface of the photo mask 100 ', the electric charge cannot be accumulated on the surface of the portion where the ground pin 250 is in contact. That is, the potential at the surface of the outer circumferential portion 160 that the ground pin 250 contacts is 0V.

Such a phenomenon may act as a factor of non-uniform electrical balance on the surface of the photo mask 100 '. That is, the portion grounded by the ground pin 250 and having a surface potential of 0 V has a potential difference with another neighboring portion having a deliberately charged surface potential, and in this neighboring portion by induction charging by such a potential difference. Will not maintain the electrical balance. Accordingly, it is not possible to keep the entire surface of the photo mask 100 'from being intentionally charged at a uniform surface potential.

14 is a view schematically illustrating a state in which a photo mask and a specimen holder are insulated according to an embodiment of the present invention.

In order to prevent the occurrence of unwanted surface potential imbalance as described above, when the sample, i.e., the photo mask 100 'is placed on the specimen holder 200 and fixed with the pin 250, the pin 250 is And the surface of the photo mask 100 'are substantially insulated. That is, by introducing an insulator 270 between the pin 250 and the chrome pattern 150 to insulate the pin 250 and the chrome pattern 150, the photo mask 100 ′ is formed by the specimen holder 200. Do not ground the surface of).

Accordingly, when the surface of the photo mask 100 ′ is intentionally charged with the ionizer 510, the chrome patterns 270 may all be intentionally charged to the same potential level, eg, −10V. As a result, a uniform level of dislocation is formed over the entire surface of the photo mask 100 ′, thereby preventing diffraction or dispersion of the electron beam when the SEM image is obtained. Therefore, the pattern shift phenomenon or the poor focus phenomenon can also be prevented from occurring in the chrome pattern 270 located at the outer portion of the photo mask 100 ', which is effective for obtaining a good SEM photograph.

15 is a view showing a measuring point for measuring the effect of the photomask surface in the non-grounding state according to the embodiment of the present invention. 16 to 19 are SEM images obtained at the points shown in FIG. 15 when the ground pin is used. 20 to 23 are SEM images obtained at the points shown in FIG. 15 when the ground pin and the photo mask surface are insulated according to an embodiment of the present invention. Figures 16 and 20 show points 1 of Figure 15, Figures 17 and 21 show points 2 of Figure 15 and Figures 18 and 22 show points 3 of Figure 15 and Figures 23 and 23 Are SEM pictures taken at the point marked 4 in FIG. 15. In both cases, SEM photographs were taken after the surface of the photomask was intentionally charged to a constant potential level, such as -10V, using an ionizer according to the present invention. In addition, the photo mask 100 ′ was mounted on the specimen holder such that the pin of the specimen holder was in contact with the chrome pattern formed on the outer peripheral portion 160. The measuring points 1, 2, 3, and 4 are positioned to be adjacent to the outer periphery of the pattern portion 130 to evaluate the difference between grounding and non-grounding of the photomask 100 ′ and the specimen holder. It was.

While the photographs of FIGS. 16 to 19 show that other patterns other than the actual patterns are photographed by the pattern shift phenomenon, FIGS. 20 to 23 clearly show the pattern shapes that are actually located, which is a pattern shift. Demonstrate that the phenomenon has been prevented.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to this, It is clear that the deformation | transformation and improvement are possible by the person of ordinary skill in the art within the technical idea of this invention.

According to the present invention described above, when SEM imaging of the surface of the sample, by intentionally providing charges such as ions or the like to the surface of the sample before SEM imaging, it is possible to suppress the occurrence of poor focus and pattern shift phenomenon at the beginning of SEM imaging. Such intentional provision of charge can be obtained by previously charging the charge on the surface of the sample to form a previous level of charge on the surface of the sample. Accordingly, it is possible to prevent the occurrence of diffraction or repulsion of primary electrons, etc. incident by the SEM imaging, thereby achieving stable SEM imaging.

Accordingly, the stabilization period can be reduced at the initial stage of SEM running. That is, the time required for obtaining a stable image by eliminating the pattern shift phenomenon and the like can be greatly reduced. As a result, in an inspection requiring very large SEM imaging, such as in analyzing a sample used for manufacturing a semiconductor device such as a photo mask, the time required for inspection can be greatly reduced, thereby improving the productivity of the semiconductor device and the quality of the product. Improvements can be implemented.

In addition, by insulating the sample surface and the sample holder, that is, by not grounding, it is possible to further prevent the pattern shift or the focus failure. As a result, it is possible to accurately and quickly obtain SEM images of the patterns of the entire area of the sample surface such as the photo mask.

Claims (23)

Scanning the target surface with a primary electron beam causing secondary electrons to be emitted from the target surface; Prior to scanning the primary electron beam, the surface of the sample is intentionally charged to increase the uniformity of the charge distribution on the surface, resulting in electrical attraction or repulsion when the primary electrons approach the surface. Reducing the tendency to diffract by; And Capturing secondary electrons emitted from the surface of the sample; Converting the captured secondary electrons into a signal; And Obtaining an image of the surface of the sample from which the primary electron beams are scanned based on the signal. The method of claim 1, wherein the step of intentionally charging the surface of the sample And providing ions to the surface of the sample. The method of claim 1, wherein intentionally charging the sample surface Providing electrons to the surface of the sample. The method of claim 1, wherein intentionally charging the sample surface Providing a charge of negative polarity to the surface of the sample. The method of claim 1, wherein intentionally charging the sample surface Providing a positive polarity charge on the surface of said sample. The method of claim 1, wherein intentionally charging the sample surface Introducing an ionizer into the sample and generating electrical charges with the ionizer to provide the charges to the sample surface. The method of claim 1, wherein intentionally charging the sample surface Introducing an electron gun into the sample and generating electrons with the electron gun to provide the electrons to the sample surface. The method of claim 1, wherein the charge level at the sample surface is measured, And wherein said step of intentionally charging a charge is performed until said charge level reaches a milestone level. The method of claim 1, wherein intentionally charging an electric charge And said sample surface is not electrically grounded. Preparing a sample consisting of a patterned conductor isolated by electrical insulators; Scanning the target surface with a primary electron beam causing secondary electrons to be emitted from the target surface; Prior to scanning the primary electron beam, the surface of the sample is intentionally charged to increase the uniformity of the charge distribution on the surface, resulting in electrical attraction or repulsion when the primary electrons approach the surface. Reducing the tendency to diffract by; And Capturing secondary electrons emitted from the surface of the sample; Converting the captured secondary electrons into a signal; And Obtaining an image of the surface of the sample on which the primary electron beams are scanned based on the signal. The method of claim 10, wherein the step of intentionally charging the surface of the sample Providing ions to the surface of said sample, wherein the scanning electron microscope image of the surface of the photomask used in the manufacture of a semiconductor device. The method of claim 10, wherein intentionally charging the sample surface Providing electrons to the surface of the sample, wherein the scanning electron microscope image of the surface of the photomask used in the manufacture of a semiconductor device. The method of claim 10, wherein intentionally charging the sample surface A method of obtaining a scanning electron microscope image of the surface of a photomask used in the manufacture of a semiconductor device, characterized by providing a negative polarity charge to the surface of the sample. The method of claim 10, wherein intentionally charging the sample surface A method of obtaining a scanning electron microscope image of the surface of a photomask used in the manufacture of a semiconductor device, characterized by providing a positive polarity charge to the surface of the sample. The method of claim 10, wherein intentionally charging the sample surface A method of obtaining a scanning electron microscope image of the surface of a photomask for use in manufacturing a semiconductor device, comprising introducing an ionizer into the sample and generating electrical charges with the ionizer to provide the charges to the sample surface. The method of claim 10, wherein intentionally charging the sample surface A method of obtaining a scanning electron microscope image of the surface of a photomask used in the manufacture of a semiconductor device, comprising introducing an electron gun into the sample and generating electrons with the electron gun to provide the electrons to the sample surface. The method of claim 10, wherein the charge level at the sample surface is measured, And wherein said step of intentionally charging a charge is performed until said charge level reaches a milestone level. 11. The method of claim 10, wherein intentionally charging the charge And said sample surface is not electrically grounded. A method of obtaining a scanning electron microscope image of the surface of a photomask used for fabricating a semiconductor device. chamber, An electron beam portion introduced into the chamber and generating a single-character electron beam to scan the beam across the surface of the specimen mounted in the chamber; A secondary electron detector which detects secondary electrons introduced into the chamber and emitted from the sample to generate a signal representative of the surface of the target from which the secondary electrons are emitted; and An image capturing unit connected to the secondary electron detection unit and including a processing unit to change the signal into an image; And And a sample processing unit connected to the image pickup unit, the sample processing unit including a charge generation unit for generating an electrical charge and providing the surface to the surface of the sample. The method of claim 19, wherein the charge generating unit It is an ionizer which provides an ion, The scanning electron microscope apparatus for obtaining the image of a sample. The method of claim 19, wherein the sample processing unit Further comprising an auxiliary chamber in which the sample is mounted, And said charge generating portion is an electron gun provided in said auxiliary chamber. The method of claim 19, A scanning electron microscope device for acquiring an image of a sample, further comprising a loader portion for moving a sample from the sample processing portion to the chamber of the image pickup portion. 20. The scanning electron microscope device of claim 19, further comprising a specimen holder used to mount the specimen, wherein the specimen holder is electrically insulated from the specimen.