JP2000348670A - Electron beam dispersing device and electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam dispersing device capable of detecting and compensating energy to be measured if it is shifted when measuring it for a long time. SOLUTION: This device is used by adding it to a microscope, and is equipped with an electron beam separating mechanism to separate an electron beam by its energy by using a magnetic field or an electric field, or the energy of the magnetic field and the electric field, and an electron beam intercepting mechanism to obtain the information of the electron beam separated by the electron beam separating mechanism by intercepting it. An electron beam detector 2 having detecting part divided into plural pieces is disposed on a part of the electron beam course between an electron beam energy filter 1 acting as the electron beam separating mechanism and the electron beam intercepting mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam spectrometer and an electron microscope using the same, and more particularly, to an electron beam spectrometer capable of performing processing corresponding to a change in measurement energy and an electron microscope using the same.

[0002]

2. Description of the Related Art There are various types of electron beam spectrometers. Most of them use a magnetic field and, depending on the type, use an electric field as an auxiliary, deflect the electron beam, and adjust the deflection angle of the electron beam. This is a device that splits the electron beam using the fact that it differs depending on the energy of the electron beam. When an electron is incident on a uniform magnetic field (magnetic field strength B) at a velocity v, the electron starts a circular motion under Lorentz force in a direction perpendicular to the direction of motion. The radius R of this circle is represented by the following equation, where m0 denotes the rest mass of the electron and c denotes the speed of light.

[0003]

(Equation 1)

Therefore, if the magnetic field strength B is constant, the orbital radius R of the electron depends only on the velocity v of the electron.
On the other hand, the kinetic energy E of the electron is expressed by the following equation.

[0005]

(Equation 2)

Since the static mass m0 of the electron is constant, the relationship between the velocity v of the electron and the kinetic energy E is univocal. Since the orbital radius R of the electron depends only on the velocity v of the electron, the orbital radius of the electron R And the kinetic energy E of the electron is also unique. Accordingly, electron beams having different kinetic energies can be separated from the deflection angle of the electrons in the magnetic field.

Various types of electron beam spectrometers have been announced by various companies, and Castan-Henry type, Omega type, Wien type, Gamma type, sector type and the like are known. Of these, Castan-Henry type, Omega type, Wien type, and Gamma type are built into the optical system of the electron microscope and integrated with the electron microscope mirror, while the sector type is mounted after the optical system of the electron microscope. It is sold like an accessory for electron microscopes.

An analysis method called electron beam energy loss spectroscopy is generally based on EELS (Electron Energy Loss).
Spectoroscopy) is a typical method of analysis using an electron beam spectrometer. The spectrum of an electron beam that has passed through a specific part of the sample (measures the magnitude of the lost energy and the probability of inelastic scattering corresponding to the energy when the electron beam loses energy when inelastically scattered in a substance) ), And the elemental composition, electronic state, thickness, optical constant, etc. of the substance can be examined.

In the electron spectroscopic imaging method, an electron beam spectroscope is used to form an image only with electrons having a specific size of energy lost or electrons having no energy loss. This is a method for observing an electronic state image and the like.

[0010] By the way, when the elemental composition and electronic state of a substance are analyzed by electron beam energy loss spectroscopy, or when the elemental composition image and electronic state image are observed by electron spectroscopic imaging, it is referred to as core loss. It is necessary to pay attention to the energy loss that occurs when electrons in the inner shell of an atom are excited. Depending on the element, the loss energy is often large when measuring core loss. Usually, as the energy loss increases, the probability decreases, and the amount of electrons to be measured decreases. For this reason, in order to analyze the element composition and the electronic state, it is necessary to lengthen the measurement time in the measurement in a region where the loss energy is large in order to make the signal integration amount appropriate.

In order to analyze the elemental composition and electronic state by electron spectroscopic imaging, it is necessary to acquire an image with at least two kinds, usually three kinds of energies.
Double or triple. At this time, it is an absolute condition that the energy of the electron beam to be measured does not change due to changes in the environment, but in reality, electron beam spectroscopy is very susceptible to external influences, In, it is difficult to make the energy to be measured constant. Therefore, when performing a long-term measurement using an electron beam spectrometer, if the energy to be measured is shifted, it is detected immediately, or the energy to be detected and measured is always It is necessary to be able to make corrections so that they do not change.

[0012]

As described above, the conventional electron beam spectrometer is susceptible to external influences, and the energy of the electron beam to be measured changes due to a change in environment, so that accurate measurement cannot be performed. There was a fear that. The present invention solves this problem, and an electronic device capable of detecting and correcting a shift in energy to be measured even when performing long-time measurement by a relatively simple method. It is an object to provide an X-ray spectrometer and an electron microscope including the same.

[0013]

According to the present invention, there is provided an electron microscope which is used in addition to an electron microscope and separates an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field. An electron beam spectroscope comprising: a beam separation mechanism; and an electron beam reception mechanism that receives an electron beam separated by the electron beam separation mechanism and obtains information on the electron beam. An electron beam detector, the detection unit of which is divided into a plurality of parts, is arranged on a part of the path of the electron beam.

Further, the present invention is used in addition to an electron microscope, and uses an electron beam separation mechanism for separating an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field. An electron beam blocking mechanism that blocks a part of the separated electron beam, and an electron beam receiving mechanism that receives an electron beam separated by the electron beam separating mechanism and that is not blocked by the electron beam blocking mechanism and obtains information therefrom. In the electron beam spectrometer provided, an electron beam detector whose detection unit is divided into a plurality is arranged near the electron beam blocking mechanism.

Further, the present invention is used in addition to an electron microscope, and uses an electron beam separation mechanism for separating an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field. In an electron beam spectroscope having an electron beam receiving mechanism for receiving the separated electron beam and obtaining the information, an electron beam detector whose detection unit is divided into a plurality is arranged near the electron beam receiving mechanism. It is characterized by the following.

Further, the present invention is characterized in that an electron microscope to which an electron beam spectrometer is added is provided with an accelerating voltage adjusting mechanism for changing an accelerating voltage of the electron microscope based on information obtained by an electron beam detector. And

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electron beam spectrometer according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show configuration diagrams of an embodiment of an electron beam spectroscope according to the present invention. In these examples, a mechanism for separating an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field is illustrated as an electron beam energy filter 1 in the drawings. The example shown in FIGS. 1 to 3 is for dispersing an electron beam around a magnetic field. 1 to 3, 1 denotes an electron beam energy filter, 2 denotes an electron beam detector, and 3, 4, and 5 denote magnetic fields.

In FIG. 1, an electron beam from the converging lens of the electron gun, which is directed from the top to the bottom of the figure, is input to the electron beam energy filter 1, and is first moved in the direction of movement by a first magnetic field 3 directed in the plane of the paper. Begins a circular motion at right angles to the direction of travel, is bent to the right with respect to the direction of travel, and further to the direction of travel by a second magnetic field 4 in the opposite direction to the first magnetic field 3 heading forward from the page. Bent to the left, first
A third magnetic field 5 in the same direction as the magnetic field 3 of FIG. 1 shows that the light beam is bent rightward with respect to the traveling direction and travels to the electron beam output mechanism via the projection lens.

In FIG. 2, the electron beam from the electron microscope main body receives a Lorentz force at right angles to the direction of motion by a magnetic field 3 directed in the direction from the plane of the drawing, and starts a circular motion. The figure shows a state of being bent toward the electron beam optical system and the electron beam receiving mechanism. 1 and 2, the electron beam detector 2 is provided at the output position of the electron beam energy filter 1.

On the other hand, the electron beam energy filter 1 shown in FIG.
Has almost the same configuration as that of FIG.
Is provided inside the electron beam energy filter 1. As described above, the electron beam detector 2 having the plurality of divided detection units is arranged at the position shown as the electron beam detector 2 in the drawing.

The detector 2 has a configuration as shown in FIG. That is, the electron beam detector 2 includes a YAG (yttrium aluminum garnet) layer 6, an optical fiber layer 7, and a photodiode array 8. When an electron beam is received, a predetermined portion of the YAG layer 6 from which the electron beam is received is received. Is emitted. The near-infrared light is transmitted to corresponding elements of the photodiode array 8 by optical fibers corresponding to respective light receiving portions of the YAG layer 6. The light receiving position of the electron beam can be determined based on which element of the photodiode array 8 has received the light, and the energy of the received electron beam can be determined. A device using a CCD instead of the photodiode array 8 may be used as a light detecting element.

When such an electron beam detector 2 is cooled using water, a Peltier element, liquid nitrogen, or the like, the S / N is improved,
High quality information can be obtained. Normally, the electron beam energy filter 1 includes a mechanism for deflecting an electron beam by a magnetic field and the like, and also includes a lens for converging the electron beam by a magnetic field and the like. Because most of the mechanisms are
As shown in (1), the electron beam detector 2 may be inside the electron beam energy filter 1 after passing through even one of the mechanisms for deflecting the electron beam. As a matter of course, the electron beam detector 2 is arranged so as to pass an electron beam in an energy region containing information to be obtained by an electron beam receiving mechanism arranged thereafter.

As the electron beam receiving mechanism, a semiconductor detector, an image pickup tube, an imaging plate, a negative film, and the like can be used as in the case of the electron beam detector. Normally, the electron beam receiving mechanism observes electrons whose energy has been lost when passing through the sample. However, as shown in FIGS. 5 and 6, the electron beam receiving mechanism is used to detect electrons having high energy which did not lose energy when passing through the sample. The line detector 2 may be arranged at a position outside the sample passing position of the electron beam.

In the electron beam spectral imaging method, it is necessary to block an electron beam in an unnecessary energy region so as not to reach the electron beam receiving mechanism. In electron beam energy loss spectroscopy, it is not always necessary to block an electron beam in an unnecessary energy region, but usually, the intensity of the electron beam in the energy region to be measured is higher than that in the unnecessary energy region. Since the intensity of an electron beam is often overwhelmingly high, it is preferable to block an electron beam in an unnecessary energy region in order to perform high-accuracy measurement at a high S / N ratio even in this case.

For these purposes, there is a mechanism provided with a mechanism such as a slit to block an extra electron beam between the time when the electron beam is split and the time when the electron beam reaches the electron beam receiving mechanism. In such an apparatus, as shown in FIGS. 7 and 8, the electron beam detector 2 is provided in direct contact with a mechanism for blocking an electron beam, or is installed in the vicinity thereof. 7 and 8, reference numeral 9 denotes a slit.

A method of arranging the electron beam detector 2 near the electron beam receiving mechanism as shown in FIGS. 9 and 10 is also conceivable. Furthermore, the electron beam detector 2 is installed on a stage that can be driven by a pulse motor, a piezo element, or the like, and can be moved in the energy spectral direction of the electron beam as shown in FIGS. Accordingly, an electron beam having a high electron beam intensity (for example, having no energy loss called zero loss) can always be measured with high energy resolution without the position of the electron beam detector 2 deviating from the electron beam to be detected. It is possible to accurately detect a change in the energy of the line.

When the spectrum measurement as shown in FIG. 13B or the observation of the energy filter image is performed by the electron beam receiving mechanism 14, the electron beam received from the electron beam detector 2 as shown in FIG. For example, the position of the zero-loss peak is detected based on the obtained spectral information, and the acceleration voltage of the electron microscope, the magnetic field intensity of the electron beam spectroscope, or the electron beam is adjusted so that the position of the zero-loss peak incident on the electron beam detector 2 is always constant. There is a method of applying feedback to the electric field intensity of the spectrometer. FIG. 14 is a block diagram showing this configuration. The spectrum information of the energy of the electron beam from the electron beam detector 2 is analyzed by the waveform analysis 21 to detect the peak position, and the electron microscope acceleration voltage 22,
Feedback is applied to one or more of the magnetic field 23 of the energy filter, the electric field 24 of the energy filter, and the electron beam deflection mechanism 25. Depending on the type of the energy filter, some of the electric field, magnetic field, and electron beam deflecting mechanisms do not exist. In an apparatus having an electron beam deflecting mechanism 25 for deflecting an electron beam as shown in FIGS. 15 and 16, an electron beam deflecting mechanism 2 for deflecting an electron beam similarly
Feed 5 back.

[0028]

As described above, the invention of claim 1 of the present invention is used in addition to an electron microscope, and separates an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field. In an electron beam spectroscope including a beam separating mechanism and an electron beam receiving mechanism that receives an electron beam separated by the electron beam separating mechanism and obtains information on the electron beam, an electron beam between the electron beam separating mechanism and the electron beam receiving mechanism is provided. An electron beam detector whose detection unit is divided into a plurality of parts is arranged on a part of the path of the line. Thus, when the energy of the electron beam to be measured changes during the measurement, it can be detected, and it is possible to take measures such as interrupting the measurement or continuing with the energy corrected.

According to a second aspect of the present invention, there is provided the electron beam spectrometer according to the first aspect, wherein the electron beam detector has an energy higher than the energy of the electron whose information is to be obtained by the electron beam receiving mechanism on the path of the electron beam. It is characterized by being arranged on a path through which electrons pass. Usually, there is the largest number of electrons that do not lose energy called zero loss, so it is most efficient to use this. Since the observation of the zero loss becomes possible, the operation of claim 1 can be efficiently obtained.

According to a third aspect of the present invention, there is provided an electron beam separating mechanism which is used in addition to an electron microscope and separates an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field. And an electron beam receiving mechanism that receives an electron beam separated by the electron beam separating mechanism and is not interrupted by the electron beam blocking mechanism and obtains information about the electron beam. In the electron beam spectrometer described above, an electron beam detector whose detection unit is divided into a plurality of parts is arranged near the electron beam blocking mechanism. This makes it possible to accurately detect a change in the energy of the electron beam to be measured. Further, in the measurement in a region where the loss energy is large, a change in the energy of the electron beam to be measured can be easily detected. Usually, the position where the slit or the like is installed is the position where the spectrum of the electron beam is projected, and the change in the energy to be measured can be sensitively measured,
It is hardly affected by the magnetic field of the energy filter or the other electron beam optical system, and the spatial arrangement can be afforded.

According to a fourth aspect of the present invention, there is provided an electron beam separating mechanism which is used in addition to an electron microscope and separates an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field. An electron beam spectroscope comprising an electron beam receiving mechanism for receiving an electron beam separated by the above and obtaining information on the electron beam is provided with an electron beam detector having a detection unit divided into a plurality of parts near the electron beam receiving mechanism. It is characterized by the following. Thereby, electron beam energy loss spectroscopy (E
When the spectrum is observed by ELS, a change in the energy of the electron beam to be measured can be detected with higher accuracy than in the case of the third aspect. Further, as in the case of the third aspect, it is hardly affected by the magnetic field of the energy filter or the other electron beam optical system, and the spatial arrangement can be given a margin.

The invention according to claim 5 is characterized in that the electron beam detector can move in a direction parallel to the direction separated by the magnitude of energy. As a result, it is possible to cope with any measurement of energy loss, and it is possible to detect an electron beam having the most sensitive energy and accurately detect a change in the energy of the electron beam.

According to a sixth aspect of the present invention, there is provided a separation intensity adjusting mechanism for changing the magnetic field intensity or the electric field intensity of the electron beam separator according to the information obtained by the electron beam detector. Thereby, even in a long-time measurement, the correction can be performed continuously without interruption, so that the deviation of the energy of the electron beam to be measured can be eliminated and accurate measurement can be performed.

According to a seventh aspect of the present invention, there is provided an electron beam deflecting mechanism provided in front of an electron beam receiving mechanism for deflecting an electron beam, and a deflection angle of the electron beam deflecting mechanism according to information obtained by an electron beam detector. And a deflection angle adjusting mechanism for changing the angle. Thereby, even in a long-time measurement, the correction can be performed continuously without interruption, so that the deviation of the energy of the electron beam to be measured can be eliminated and accurate measurement can be performed.

According to an eighth aspect of the present invention, there is provided an electron microscope to which the electron beam spectrometer according to any one of the first to seventh aspects is added, wherein the information obtained by the electron beam detector accelerates the electron microscope. It is characterized by comprising an accelerating voltage adjusting mechanism for changing the voltage. This makes it possible to perform continuous correction without interruption even when performing long-term measurement in an electron microscope, and to achieve accurate measurement by eliminating the energy deviation of the electron beam to be measured. Become.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of an electron beam spectrometer of the present invention.

FIG. 2 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 3 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 4 is a configuration diagram of an electron beam detector used in the embodiment of the electron beam spectrometer of the present invention.

FIG. 5 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 6 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 7 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 8 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 9 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 10 is a configuration diagram of an embodiment of an electron microscope of the present invention.

FIG. 11 is a configuration diagram of an embodiment of an electron beam spectrometer of the present invention.

FIG. 12 is a configuration diagram of an embodiment of an electron beam spectrometer according to the present invention.

FIG. 13 is a configuration diagram of an embodiment of an electron microscope of the present invention.

FIG. 14 is a block diagram of a feedback system of the electron beam spectrometer of the present invention.

FIG. 15 is a configuration diagram of an embodiment of an electron beam spectrometer of the present invention.

FIG. 16 is a configuration diagram of an embodiment of an electron microscope of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electron beam energy filter 2 electron beam detector 3, 4, 5 magnetic field 6 YAG layer 7 optical fiber layer 8 photodiode array 9 slit 10 sample 11 objective lens 12 intermediate lens 13 projection lens 14 electron beam receiving mechanism 15 electron microscope 16 electron beam Optical system 21 Waveform analysis 22 Acceleration voltage of electron microscope 23 Energy filter magnetic field 24 Energy filter electric field 25 Electron beam deflection mechanism

Claims (8)

[Claims] An electron beam separation mechanism used in addition to an electron microscope to separate an electron beam by its energy using a magnetic field or an electric field, or a magnetic field and an electric field, and an electron separated by the electron beam separation mechanism An electron beam spectroscope comprising: an electron beam receiving mechanism that receives a line and obtains information on the electron beam. An electron beam spectroscopic device, comprising: a detection unit provided on a part of the path of the electron beam between the electron beam separating mechanism and the electron beam receiving mechanism. An electron beam spectrometer characterized by arranging a plurality of divided electron beam detectors. 2. The method according to claim 1, wherein the electron beam detector is arranged on a path through which electrons having an energy higher than the energy of the electrons whose information is to be obtained by the electron beam receiving mechanism pass on the path of the electron beam. The electron beam spectroscope according to claim 1, wherein: 3. An electron beam separation mechanism that is used in addition to an electron microscope and separates an electron beam by its energy using a magnetic field or an electric field, or a magnetic field and an electric field, and an electron separated by the electron beam separation mechanism. An electron beam, comprising: an electron beam blocking mechanism for blocking a part of a beam; and an electron beam receiving mechanism for receiving an electron beam separated by the electron beam separating mechanism and not blocked by the electron beam blocking mechanism and obtaining information thereof. An electron beam spectrometer, wherein an electron beam detector whose detection unit is divided into a plurality of parts is arranged near the electron beam cutoff mechanism. 4. An electron beam separation mechanism used in addition to an electron microscope to separate an electron beam by its energy using a magnetic field or an electric field or a magnetic field and an electric field, and an electron separated by the electron beam separation mechanism. An electron beam spectroscopic apparatus comprising: an electron beam receiving mechanism that receives a beam and obtains information about the beam. An electron beam spectroscope, comprising: an electron beam detector whose detection unit is divided into a plurality of parts near the electron beam receiving mechanism. Electron beam spectrometer. 5. The electron beam spectroscope according to claim 1, wherein the electron beam detector is movable in a direction parallel to a direction separated by the magnitude of the energy. 6. The apparatus according to claim 1, further comprising a separation intensity adjusting mechanism for changing a magnetic field intensity or an electric field intensity of said electron beam separator in accordance with information obtained by said electron beam detector. 5. The electron beam spectrometer according to any one of 4. 7. An electron beam deflecting mechanism provided before the electron beam receiving mechanism for deflecting an electron beam, and changing a deflection angle of the electron beam deflecting mechanism according to information obtained by the electron beam detector. The electron beam spectroscope according to any one of claims 1 to 6, further comprising a deflection angle adjusting mechanism for causing the electron beam to be deflected. 8. An electron microscope to which the electron beam spectrometer device according to claim 1 is added, wherein acceleration obtained by changing an accelerating voltage of the electron microscope according to information obtained by an electron beam detector. An electron microscope comprising a voltage adjusting mechanism.