WO2013062158A1 - Scanning electron microscope having an electronic beam aligning function, and method for controlling a wien filter for a scanning electron microscope - Google Patents

Abstract

The present invention relates to a method for controlling a Wien filter for a scanning electron microscope. The method for controlling the Wien filter for the scanning electron microscope is used for a scanning electron microscope which detects electrons by passing them through the Wien filter and making same enter a detector, wherein the electrons are emitted after electronic beams generated from a light source enter a sample through the Wien filter. The method is characterized by including: the production of a final electric field and a final magnetic field which are applied to the Wien filter to allow the electronic beams passing through the Wien filter to reach a target point on the sample and, at the same time, to allow the electrons emitted from the sample and passing through the Wien filter to reach the detector; and the application of the final electric field and final magnetic field to the Wien filter.

Description

Scanning electron microscope with empty filter control method and scanning electron microscope

The present invention relates to an empty filter control method for a scanning electron microscope and a scanning electron microscope having an electron beam alignment function. More particularly, the scanning electron microscope can be aligned to achieve a desired target point by using an empty filter. The present invention relates to a scanning electron microscope having an empty filter control method and an electron beam alignment function.

Recently, information on microstructures or material surface shapes is urgently needed due to the industrialization of micro technology in the field of advanced materials as well as minimization of information devices. In particular, as nanotechnology has been actively researched around the world since the late 1990s, various studies have been conducted to investigate the structure and properties of nanomaterials, and electron microscopy plays an important role.

Recently, the surface of a sample placed in a vacuum is scanned in a two-dimensional direction with a fine electron beam of about 1 to 100 nm to detect a signal of secondary electrons generated on the surface of the sample, and to display or record an enlarged image on a cathode ray and a screen, Scanning electron microscopes for analyzing morphological microstructures and the like are widely used.

However, in the related art, a separate positioning device is required to align the moving trajectory of the electron beam so that the emitted electron beam may reach a desired target point.

In addition, there is a problem that the reliability at the time of sample measurement is lowered due to the deformation of the cross-sectional shape during the electron beam movement.

Accordingly, an object of the present invention is to solve such a conventional problem, the empty filter control method for a scanning electron microscope that can be controlled to reach the desired target point on the sample by using the empty filter without any additional device and A scanning electron microscope having an electron beam alignment function is provided.

The above object is, according to the present invention, a method used in a scanning electron microscope for detecting an electron beam generated from a light source through an empty filter and incident on a sample, and then emitting electrons emitted through the empty filter and incident on a detector. And the final electric field and the final electric field to be applied to the empty filter so that the electron beam passing through the empty filter reaches the target point of the sample and at the same time the emitted electrons passing through the empty filter reach the detector. Calculating a magnetic field; And applying the final electric field and the final magnetic field to the empty filter. The empty filter control method for a scanning electron microscope, comprising: a.

In the calculating step, an initial electric field is applied to the empty filter so that the electron beam passing through the empty filter moves vertically downwards, and at the same time, the emission electrons emitted from the sample and passing through the empty filter reach the detector. And an initial information acquiring step of acquiring an initial magnetic field. And obtaining alignment information for obtaining an alignment electric field and an alignment magnetic field to be applied to the empty filter so that the electron beam reaches the target point of the sample.

The method may further include a correction information obtaining step of obtaining a correction electric field required for the empty filter to correct the cross-sectional shape of the electron beam before the applying step, wherein the applying step is applied to the empty filter in the correcting electric field obtaining step. The final electric field may include the corrected electric field information.

The alignment information acquiring step may include: a target point acquiring step of acquiring a position of the target point on the sample; A distance measuring step of measuring the target point linear distance from the bin filter; And a final horizontal force calculation step of calculating a final horizontal force to be provided to the electron beam from the empty filter in order for the electron beam to reach a position of the target point.

In addition, the alignment information acquiring step is required after the final horizontal force calculation step, so that the final horizontal force is applied to the electron beam and the emission electrons passing through the empty filter reach the detector. The method may further include calculating alignment information for calculating the alignment electric field and the alignment magnetic field.

In addition, the electrostatic force applied to the electron beam by the alignment electric field may have the same magnitude in the same direction as the magnetic force applied to the electron beam by the alignment magnetic field.

The object is, according to the present invention, a scanning electron microscope for injecting an electron beam generated from a light source into a sample to measure the emitted electrons emitted from the sample, wherein the scanning electron microscope is disposed between the sample and the sample to detect the emitted electrons. Detector; A bin filter disposed below the detector and configured to control a movement trajectory of the electron beam and the emission electrons by generating a magnetic field and an electric field; Control unit for controlling the electric and magnetic fields applied to the empty filter is achieved by a scanning electron microscope having an electron beam alignment function.

The control unit may further include a first calculation unit configured to calculate an initial electric field and an initial magnetic field applied to the empty filter so that the electron beam passing through the empty filter moves vertically downward; And a second calculation unit configured to calculate an alignment electric field and an alignment magnetic field applied to the empty filter so that the electron beam reaches a desired target point on the sample.

The control unit may further include a third calculator configured to calculate a correction electric field applied to the empty filter in order to control the shape of the cross section of the electron beam passing through the empty filter.

According to the present invention, there is provided an empty filter control method for a scanning electron microscope that can easily control a movement trajectory of an electron beam by using an empty filter.

In addition, the shape deformation of the electron beam can be easily corrected by using the empty filter.

In addition, according to the present invention, there is provided a scanning electron microscope having an electron beam alignment function that can easily control the movement trajectory and shape of an electron beam by using an empty filter.

1 schematically illustrates a scanning electron microscope with an electron beam alignment function according to an embodiment of the present invention,

FIG. 2 schematically illustrates the empty filter of the scanning electron microscope with the electron beam alignment function of FIG. 1,

3 is a flowchart of a method of controlling a blank filter for a scanning electron microscope according to a first embodiment of the present invention;

4 is for explaining the initial information acquisition step of the empty filter control method for the scanning electron microscope of FIG.

5 is for explaining a target point acquisition step of the empty filter control method for the scanning electron microscope of FIG.

FIG. 6 illustrates an operation of calculating alignment information of the empty filter control method for the scanning electron microscope of FIG. 3.

FIG. 7 illustrates an application step of the empty filter control method for the scanning electron microscope of FIG. 3.

8 is a flowchart of a method of controlling a blank filter for a scanning electron microscope according to a second embodiment of the present invention;

FIG. 9 illustrates an operation of obtaining correction information of the empty filter control method for the scanning electron microscope of FIG. 8.

Prior to the description, in the various embodiments, components having the same configuration will be representatively described in the first embodiment using the same reference numerals, and in other embodiments, different configurations from the first embodiment will be described. do.

Hereinafter, an empty filter control method for a scanning electron microscope according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Before describing the empty filter control method (S100) for the scanning electron microscope according to the first embodiment of the present invention, the scanning electron microscope (100) having an electron beam alignment function used in the method of the present embodiment and a measuring method using the same This is described first.

Figure 1 schematically shows a scanning electron microscope with an electron beam alignment function according to an embodiment of the present invention.

Referring to FIG. 1, the scanning electron microscope 100 having the electron beam alignment function includes a barrel 110, a light source 120, a focusing lens 130, an aperture 140, a detector 150, and an empty filter. 160, an objective lens 170, a sample holder 180, and a controller 190.

The barrel 110 is an exterior material for accommodating the light source 120, the focusing lens 130, the aperture 140, the detector 150, the bin filter 160, and the objective lens 170, which will be described later. The end of the side from which the electron beam exits, that is, the end of the sample side on which the sample is mounted, is configured to maintain the vacuum state.

The light source 120 is a member for scanning the electron beam generated by heating the cathode in the barrel 110 toward the sample holder 180 on which the lower sample S is mounted.

The focusing lens 130 is a member for focusing the electron beam emitted from the light source 120 described above.

The aperture 140 is a member for converting the focused electron beam into a constant wavelength by passing through the focusing lens 130.

The detector 150 is a member for detecting electrons emitted from the sample S after the electron beam is incident, that is, emission electrons including secondary electrons. Disposed between filters 160.

On the other hand, since the emitted electrons are deflected laterally by the empty filter 160 and are incident on the detector 150 while moving upward from the sample S, the front end surface of the detector 150 may receive the emitted electrons vertically. It is desirable to form a slope so that it can.

FIG. 2 schematically illustrates the empty filter of the scanning electron microscope with the electron beam alignment function of FIG. 1.

Referring to FIG. 2, the empty filter 160 is provided between the detector 150 and the sample holder 180, that is, the lower side of the detector 150, and the empty filter 160 passes downward. It is a member for controlling the movement trajectory of the electron beam to reach this desired target point or controlling the movement trajectory of the emission electrons so that the emission electrons passing upward are deflected toward the detector 150.

On the other hand, the empty filter 160 is composed of an electric field generating unit for generating an electric field by applying an applied voltage to apply an electrostatic force to the electron beam or emitting electrons, and a magnetic field generating unit for generating a magnetic field to apply a magnetic force to the moving electron beam or emitting electrons A plurality of pole electrodes 161 are mounted around the ring-shaped support member 162 surrounding the movement trajectory of the electron beam or the emission electrons.

Meanwhile, in the present embodiment, the number of pole electrodes 161 is described as eight, but the number of pole electrodes 161 is not limited thereto.

The control unit 190 is to control the electric and magnetic fields generated from the empty filter 160, the application unit 191, the first output unit 192, the second output unit 193 and the third output unit ( 194).

The applying unit 191 is connected to the first calculating unit 192, the second calculating unit 193, and the third calculating unit 194, which will be described later, is obtained from the calculation units 192, 193, and 194. The final electric field and the final magnetic field information is applied to the empty filter 160.

The first calculation unit 192 allows the electron beam generated from the upper light source 120 to move vertically downward without being deflected, so that the emission electrons emitted from the lower sample S are incident on the detector 150. It is a member for calculating the initial electric field and the initial magnetic field information required from the empty filter 160 to deflect the movement traces of the emission electrons.

The second calculation unit 193 does not affect the movement trajectory of the emission electrons emitted from the sample S, and the empty filter 160 to concentrate the electron beam emitted from the light source 120 at a desired target point of the sample. Is a member for calculating the alignment electric field and alignment magnetic field information required from the.

That is, since the electric field and the magnetic field required from the empty filter 160 to deflect the emitted electrons toward the detector 150 are calculated by the first calculating unit 192, the second calculating unit 193 aligns the electron beam to a desired target point. In order to calculate the alignment electric field and the alignment magnetic field information required from the empty filter 160.

The third calculation unit 194 is a member that calculates correction electric field information required from the empty filter 160 to control the shape of the cross section of the electron beam emitted from the light source 120.

 In other words, when the electron beam passes through the empty filter 160, the cross section of the electron beam may be non-circular in the moving direction and the cross section in the vertical direction. When the electron beam crosses the cross section, the reliability of the measurement result of the sample S may be ensured. Since it is not possible to apply an additional correction electric field from the empty filter 160 to correct the shape of the electron beam.

Therefore, the third calculation unit 194 calculates the information of the electric field required from the empty filter 160 to correct the shape of the electron beam and provides it to the application unit 191 described above.

The operation of the scanning electron microscope with the electron beam alignment function described above will now be briefly described.

First, the electron beam scanned from the light source 120 reaches the empty filter 160 after passing through the focusing lens 130 and the aperture 140. In this case, the empty filter 160 generates the final electric field and the final magnetic field by the controller 190.

The electron beam applied with electrostatic force and magnetic force by the electric and magnetic fields generated from the empty filter 160 passes through the objective lens 170 to reach the target point on the sample S. After the electron beam is incident, 2 Emitting electrons, including the charge electrons, are emitted.

The emission electrons move upward and pass through the empty filter 160. The emission electrons affected by the electrostatic and magnetic forces by the final electric field and the final magnetic field applied from the empty filter 160 move to the detector 150. It is deflected and detected by the last incident on the detector 150.

Meanwhile, a first embodiment of the method for controlling the empty filter in the operation of the scanning electron microscope with the electron beam alignment function described above will be described in detail below.

3 is a flowchart of a method of controlling an empty filter for a scanning electron microscope according to a first embodiment of the present invention.

Referring to FIG. 3, the scanning filter microscopy empty filter control method (S100) according to the first exemplary embodiment of the present invention is for aligning an electron beam using the empty filter 160. (S120).

The calculating step S110 is a step of calculating and obtaining final electric field and final magnetic field information applied to the empty filter 160, and includes an initial information obtaining step S111 and an alignment information obtaining step S112.

FIG. 4 illustrates an initial information acquisition step of the empty filter control method for the scanning electron microscope of FIG. 3.

Referring to FIG. 4, in the initial information acquiring step S111, the electron beam passing downward through the empty filter 160 is moved vertically downward without deflection of the trajectory, and simultaneously passes upward through the empty filter 160. The movement trajectory of the emitted electrons is deflected to calculate and obtain the initial electric field and the initial magnetic field information required from the empty filter in order for the emitted electrons to move toward the detector 150 through the first calculation unit 192.

In other words, it is assumed that the region of the sample S to be measured is in a state vertically below the empty filter 160, and this state is defined as an initial state. In this initial state, the trajectory change of the electron beam due to the empty filter 160 is not required, and only the movement trajectory of the emission electrons is deflected toward the detector 150.

Therefore, in the first calculation unit 192, the electrostatic force F _{M, I1} applied to the electron beam and the electrostatic force F _{M, I2} applied to the emission electrons are the same, but the magnetic force F _{E, I1} applied to the electron beam is the same. The magnetic force F _{E, I2} applied to the emission electrons sets the initial electric field and the initial magnetic field information to have the same intensity in the opposite direction.

In the obtaining of the alignment information (S112), when the incident target point of the electron beam is not vertically downward, the second field unit 193 receives the alignment electric field and the alignment magnetic field information required for the empty filter 160 to align the electron beam. The calculating and acquiring step includes a target point obtaining step S113, a distance measuring step S114, a final horizontal force calculating step S115, and an alignment information calculating step S116.

5 is for explaining a target point acquisition step of the empty filter control method for the scanning electron microscope of FIG.

Referring to FIG. 5, the target point obtaining step S113 is a step of receiving a target point T on the sample S from the outside or by specifying an arbitrary target point T internally.

The distance measuring step S114 is a step of detecting or measuring the linear distance d from the position of the empty filter 160 to which the electrostatic force and the magnetic force are applied to the electron beam from the target point T of the sample S.

The final horizontal force calculating step (S115) is a target point in consideration of the linear distance (d) from the empty filter 160 measured in the above-described distance measuring step (S114) to the target point (T) and the moving speed of the electron beam. It is a step of calculating the horizontal force, that is, the final horizontal force, which should be applied to the electron beam in order to reach (T).

FIG. 6 illustrates an operation of calculating alignment information of the empty filter control method for the scanning electron microscope of FIG. 3.

Referring to FIG. 6, in the alignment information calculating step S116, the final horizontal force calculated in the final horizontal force calculating step S115 is provided to the electron beam, but the empty filter 160 does not affect the emitted electrons. Calculating the required alignment electric field and the alignment magnetic field.

That is, in this step, the combination of the electrostatic force (F _{M, A1} ) and the magnetic force (F _{E, A1} ) applied to the electron beam passing downward through the empty filter 160 is the first horizontal force, but the empty filter ( Electrostatic forces (F _{M, A2} ) and magnetic forces (F _{E, A2} ) applied to the emission electrons passing upward through 160 are canceled to calculate the alignment electric field and the alignment magnetic field so as not to affect the emission electrons.

FIG. 7 illustrates an application step of the empty filter control method for the scanning electron microscope of FIG. 3.

Referring to FIG. 7, the applying step S120 calculates the final electric field and the final magnetic field by combining the initial electric field, the initial magnetic field and the alignment electric field, and the alignment magnetic field obtained in the calculating step S110. By using this to generate the final electric field and the final magnetic field from the empty filter 160, the electron beam passing through the empty filter 160 to reach the desired target point (T) on the sample (S) while being emitted from the sample (S) The emission electrons are controlled to be incident on the detector 150.

In other words, in this step, the applying unit 191 calculates the initial electric field and initial magnetic field information calculated and obtained by the first calculating unit 192 and the correction electric field and correction magnetic field information obtained by the second calculating unit 193. By integrating, the final and final magnetic fields are calculated and the final and final magnetic fields are generated from the empty filter.

Next, the empty filter control method (S200) for the scanning electron microscope according to the second embodiment of the present invention will be described later.

8 is a flowchart of a method of controlling a blank filter for a scanning electron microscope according to a second embodiment of the present invention.

Referring to FIG. 8, the scanning filter microscopic empty filter control method (S200) according to the second exemplary embodiment of the present invention is for aligning an electron beam using the empty filter 160. (S120).

The calculating step (S110) is a step of calculating and obtaining final electric field and final magnetic field information applied to the empty filter 160. The initial information obtaining step (S111), the alignment information obtaining step (S112), and the correction information obtaining step ( S217), and the initial information acquiring step S111 and the alignment information acquiring step S112 are the same as described above in the first embodiment, and thus redundant description is omitted.

FIG. 9 illustrates an operation of obtaining correction information of the empty filter control method for the scanning electron microscope of FIG. 8.

Referring to FIG. 9, the correction information acquiring step S217 may remove the correction electric field required from the empty filter 160 to correct the abnormal shape of the electron beam passing through the empty filter 160 to the normal shape. It is the step of calculating and acquiring through the three calculating unit 194.

That is, when measuring the sample S using the abnormal electron beam, such as the case where the shape of the cross section perpendicular to the moving direction of the electron beam is not a circular shape, the measurement S reliability decreases, and thus, the third calculation unit 194 ) Calculates the correction electric field information required from the empty filter 160 to correct this. In other words, the third calculation unit 194 calculates a correction electric field required from the empty filter 160 in order for the electrostatic force F _C applied to the electron beam to correct the shape of the electron beam.

Therefore, the calculated corrected electric field information is transmitted to the applying unit 191, and in the applying step (S191), the final electric field in consideration of the corrected electric field information is generated from the empty filter 160.

The scope of the present invention is not limited to the above-described embodiment, but may be embodied in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the invention claimed in the claims, it is intended that any person skilled in the art to which the present invention pertains falls within the scope of the claims described in the present invention to various extents which can be modified.

The empty filter control method for a scanning electron microscope which can control an electron beam to reach a desired target point on a sample using an empty filter without a separate additional apparatus is provided.

Claims (9)

A method used in a scanning electron microscope for detecting an electron beam generated from a light source by passing through a bin filter and entering a sample and then emitting emitted electrons through the bin filter and entering the detector. The final electric field and the final magnetic field that must be applied to the empty filter so that the electron beam passing through the empty filter reaches the target point of the sample and at the same time, the emission electrons emitted from the sample and passing through the empty filter reach the detector. Calculating step of calculating; And an applying step of applying the final electric field and the final magnetic field to the empty filter. The method of claim 1, The calculating step includes an initial electric field and an initial stage applied to the empty filter so that the electron beam passing through the empty filter is moved vertically downward and at the same time, the electrons emitted from the sample to pass through the empty filter reach the detector. Initial information obtaining step of obtaining a magnetic field; And an alignment information acquiring step of acquiring an alignment electric field and an alignment magnetic field to be applied to the empty filter so that the electron beam reaches a target point of the sample. The method of claim 2, And a correction information acquiring step of acquiring a correction electric field required for the empty filter to correct the cross-sectional shape of the electron beam before the applying step. And in the applying step, the final electric field applied to the empty filter in the obtaining correction information includes the corrected electric field information. The method of claim 2, The alignment information acquiring step may include: a target point acquiring step of acquiring a position of the target point on the sample; A distance measuring step of measuring the target point linear distance from the bin filter; And a final horizontal force calculation step of calculating a final horizontal force to be provided to the electron beam from the empty filter so that the electron beam reaches the position of the target point. The method of claim 4, wherein The obtaining of the alignment information is performed after the final horizontal force calculating step, And an alignment information calculating step of calculating an alignment electric field and an alignment magnetic field required from the empty filter to allow the final horizontal force to be applied to the electron beam and to allow the emission electrons passing through the empty filter to reach the detector. Empty filter control method for a scanning electron microscope, characterized in that. The method of claim 5, The electrostatic force applied to the electron beam by the alignment electric field has the same magnitude in the same direction as the magnetic force applied to the electron beam by the alignment magnetic field. In a scanning electron microscope for measuring the emission electrons emitted from the sample by injecting an electron beam generated from the light source into the sample, A detector disposed between the sample and the sample and detecting the emission electrons; A bin filter disposed below the detector and configured to control a movement trajectory of the electron beam and the emission electrons by generating a magnetic field and an electric field; And a control unit for controlling an electric field and a magnetic field applied to the empty filter. The scanning electron microscope having an electron beam alignment function of the empty filter. The method of claim 6, The control unit may include a first calculation unit configured to calculate an initial electric field and an initial magnetic field applied to the empty filter so that the electron beam passing through the empty filter moves vertically downward; And a second calculation unit configured to calculate an alignment electric field and an alignment magnetic field applied to the empty filter so that the electron beam reaches a desired target point on the sample. The method according to claim 6 or 7, And the control unit further comprises a third calculation unit for calculating a correction electric field applied to the empty filter to control the shape of the cross section of the electron beam passing through the empty filter.

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