JPH11307031A - Analytic electron microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set both the mode of electron microscope and the mode of fluorescent X-ray analyzer by one apparatus, and to form extrafine X-ray beams without lowering utilizing efficiency of the X-rays in the mode of fluorescent X-ray analyzer. SOLUTION: In this analytical electron microscope 1, when a target 10 is inserted between an objectless 8 and a sample 9, the mode of fluorescent X-ray analyzer is set, and when the target 10 is removed from between them, the mode of scanning electron microscope is set. In the mode of fluorescence X-ray analyzer, valve operation of a supporting member 12 of the target 10 airtightly blocks the electron ray generating side A from the sample 9 side B, within a casing 4. Thereby, the sample 9 side B can be set in atmosphere of the room air or helium, with the electron ray generating side A being held with high vacuum. Thus, one analytic electron microscope can carry out both the function of the fluorescence X-ray analyzer and the function of the scanning electron microscope.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an analytical electron microscope having both functions of an electron microscope and a function of an X-ray fluorescence analyzer.

[0002]

2. Description of the Related Art Conventionally, an analyzer for performing elemental analysis on a minute portion of a sample has been developed.
There are a device in which an X-ray detector is attached to an electron microscope, and a fluorescent X-ray analyzer.

An apparatus in which an X-ray detector is attached to an electron microscope accelerates an electron beam emitted from an electron gun and irradiates the sample with a focus so as to focus on the surface of the sample.
X-rays are generated, and the characteristic X-rays are detected by an X-ray detector. By measuring the energy of the X-rays with an X-ray analyzer, the types and amounts of the elements constituting the sample are analyzed.

[0004] When the elemental analysis of a sample is performed using an apparatus in which an X-ray detector is attached to an electron microscope, there are the following problems. That is, in this apparatus, since the sample chamber must be evacuated, a sample having a high vapor pressure cannot be analyzed. In addition, since the irradiation position fluctuates due to the charging of the sample by electrons, and the irradiation current becomes unstable,
Insulators cannot be analyzed as is. Furthermore, since the vacuum residual gas component is burned on the sample surface by the electron beam irradiation, the sample is contaminated. Further, since the background due to the bremsstrahlung X-rays is large, the detection limit is worse than that of the fluorescent X-ray analyzer.

[0005] Therefore, a fluorescent X-ray analyzer has been conventionally developed which eliminates the problems of an apparatus having an X-ray detector attached to an electron microscope. This X-ray fluorescence analyzer irradiates a sample with X-rays emitted from a microfocus X-ray tube, generates characteristic X-rays from the sample, and measures the characteristic X-rays by spectroscopy. .

[0006]

However, the fluorescent X
When performing elemental analysis of a sample with a line analyzer, there are the following problems. That is, since a microfocus X-ray tube is used, it is difficult to produce a beam having a high brightness and a very small diameter.
This means that in order to perform elemental analysis in a minute part, the X-ray is required to be a very fine beam with a focal diameter of about 1 to 10 μφ and a high brightness. This is because the focal diameter of the X-ray is about 100 μφ. Therefore, conventionally, an X-ray beam from a microfocal X-ray tube is restricted by an orifice to form an ultrafine X-ray beam.
The line use efficiency becomes extremely poor.

In addition, the low-energy X-ray excitation efficiency becomes extremely low due to the absorption of low-energy components contained in the primary X-rays by the window material of the tube. That is, the accuracy of light element analysis is reduced.

Further, not only two electron microscopes and two fluorescent X-ray analyzers must be prepared for analysis, but also the electron microscope and the fluorescent X-ray analyzer must be properly used depending on the analysis object and purpose. No, the work is troublesome.

The present invention has been made in view of such circumstances, and a purpose thereof is to set a mode of an electron microscope and a mode of an X-ray fluorescence analyzer with one unit, and to analyze these modes for analysis. By switching according to the purpose and the purpose, it is possible to perform the analysis under the optimum conditions, and when the X-ray fluorescence analyzer mode is set, the ultra-fine X-ray can be used without lowering the X-ray utilization efficiency.
It is to provide an analytical electron microscope capable of forming a line beam.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention of claim 1 provides an electron gun for emitting an electron beam, a lens for converging the electron beam, a lens for converging the electron beam, and the like. A sample supporter disposed below and on the center axis of the electron gun for supporting the sample, and detecting X-rays generated from the sample in the casing.
In an electron microscope equipped with a line detector, a target is provided between the lens and the sample supporting portion so as to be movable between a use position on the central axis and an unused position off the central axis. When the target is set at the use position, the electron beam irradiates the target, so that X-rays generated from the target irradiate the sample, and the fluorescent X-rays generated from the sample are converted into the X-rays. X-ray fluorescence spectroscopy mode for detecting with the X-ray detector, and when the target is set at the non-use position, the characteristic X-ray generated from the sample by irradiating the sample with the electron beam is converted into the X-ray. An electron microscope mode for detection by a detector is set.

The invention according to claim 2 is characterized in that when a plurality of the lenses are provided, the target is provided between the lenses. Furthermore, a third aspect of the present invention is characterized in that a collimator which is located on the central axis and located on the center axis side from the use position of the target and which restricts X-rays is provided.

Further, according to a fourth aspect of the present invention, the target is fixedly supported by a support member movably provided on the casing, and the support member is electrically connected to the target when the target is located at a use position. It is preferable that the valve is configured to hermetically shut off the electron beam generator and the sample when the target is located at the non-use position. Features.

[0013]

In the analytical electron microscope according to the first and second aspects of the present invention, the X-ray fluorescence analyzer mode is set by setting the target at the use position. As a result, the analytical electron microscope exhibits the same function as a conventional fluorescent X-ray analyzer for measuring a minute part of a sample. Further, by setting the target to the unused position, the electron microscope mode is set. As a result, the analytical electron microscope exhibits the same function as the conventional electron microscope. That is, the analytical electron microscope
A single unit has both the function of an electron microscope and the function of a fluorescent X-ray analyzer, and by appropriately switching between these two functions depending on the analysis object and purpose, analysis under optimal conditions becomes possible.

In particular, in the third aspect of the present invention, since the X-rays for irradiating the sample are limited by the collimator, a fine focus of the X-rays with higher brightness can be easily obtained. Therefore, since the X-ray beam from the target is extremely thin, the use efficiency of X-rays is extremely high as compared with the X-ray tube in the conventional X-ray fluorescence analyzer, and high-sensitivity analysis is performed.

Further, in the invention according to claim 4, when the support member for fixing and supporting the target positions the target at the use position, the electron beam generating unit side and the sample side are hermetically shut off. Become. Therefore, it is possible to set the sample side to the atmosphere or the helium atmosphere while keeping the electron beam generating unit side at a high vacuum.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically illustrating an example of an embodiment of an analytical electron microscope according to the present invention.

As shown in FIG. 1, an analytical electron microscope 1 of this embodiment is configured by attaching an X-ray detector 3 to a scanning electron microscope 2 like a conventional analytical electron microscope.
The scanning electron microscope is conventionally known, and includes an electron gun 5, an anode 6, a condenser lens 7, and an objective lens 8 in a casing 4. Further, the analytical electron microscope 1 is provided with a target 10 made of a metal thin film provided between the objective lens 8 and a sample support 9 a for supporting the sample 9, and provided between the target 10 and the sample 9. , And a collimator 11 for limiting X-rays.

As shown in FIG. 2, the target 10 is hermetically supported and fixed to a support member 12. This support member 1
Reference numeral 2 denotes an airtight and slidable seal member 13 such as an O-ring provided on the lower surface of an intermediate horizontal floor 4a of the casing 4 disposed immediately below the objective lens 8. The support member 12, that is, the target 10 is movable between the position of the center axis α of the electron gun 5 shown by the solid line in FIG. 2, that is, the use position and the non-use position shown by the two-dot chain line. The movement of the support member 12 is performed by the operation member 14. A hole 4b concentric with the central axis α of the electron gun 5 is formed in the horizontal floor 4a.
A hole 12a concentric with the hole 4b is formed in the support portion of the support member 12.

When the support member 12, that is, the target 10 is set to the use position shown by the solid line in FIG. 2, the inside of the casing 4 of the electron microscope 2 is divided into the electron beam generating side A and the sample 9 side B.
When the support member 12, that is, the target 10 is set at an unused position indicated by a two-dot line in FIG. 2, the inside of the casing 4 of the electron microscope 2 is separated from the electron beam generator side A with the sample. It communicates with the 9 side B. That is, the support member 12 of the target 10 also serves as a gate valve for airtightly shutting off the communication between the electron beam generating unit side A and the sample 9 side B. Thereby, the sample 9 side can be set to the atmosphere or the helium atmosphere while the electron beam generating section A side is kept in a high vacuum.

The focal point of the electron beam is focused on the surface of the sample 9 when the target 10 is set at the non-use position, and is focused on the surface of the target 10 when the target 10 is set at the use position. The switching is controlled so as to be connected to. This switching of the focus is performed in conjunction with the movement of the target 10. In the analytical electron microscope 1 of this example, since the electron beam is set to be focused on the target 10, the target 10
To prevent damage due to heat generated by electron beam irradiation,
Although not shown, cooling is performed by an appropriate cooling means.

In the thus constructed analytical electron microscope 1 of this example, when the target 10 is set at the use position, that is, when the target 10 is inserted between the objective lens 8 and the sample 9, the fluorescent X-ray analysis is performed. When the apparatus mode is set and the target 10 is removed from between them, the scanning electron microscope mode is set.

When the fluorescent X-ray analyzer mode is set,
The electron beam emitted from the electron gun 5 is accelerated and focuses on the target 10. At this time, X-rays are generated from the target 10 by irradiating the target 10 with the electron beam. The X-rays pass through the metal thin film target 10 and irradiate the sample 9. As a result, fluorescent X-rays are generated from the sample 9 and the generated fluorescent X-rays
The X-ray is detected by the X-ray detector 3 and analyzed by an X-ray analyzer in a conventional manner.

On the other hand, when the scanning electron microscope mode is set, the electron beam emitted from the electron gun 5 is accelerated so as to be focused on the sample 9, and is scanned by the same scanning electron microscope as in the prior art. The analysis of the sample 9 is performed.

According to the analytical electron microscope 1 of this embodiment, the electron beam from the electron gun 5 is focused on the surface of the sample 9 with the target 10 detached from the support member 12 so that the sample 9 is By irradiating, the same function as the conventional scanning electron microscope 2 can be exhibited, and the electron beam from the electron gun 5 is focused on the target 10 while the target 10 is supported by the support member 12.
By irradiating the target 10 so as to be connected to the surface of the sample, the function of a conventional fluorescent X-ray analyzer for measuring a minute portion of the sample 9 can be exhibited. That is, the analytical electron microscope 1 of this example is an apparatus having both the function of the scanning electron microscope 2 and the function of the X-ray fluorescence spectrometer, and by optimally switching these two functions depending on the analysis target and the purpose, the optimum. Analysis under conditions becomes possible.

Further, by merely installing the target 10 and the collimator 11 on the conventional scanning electron microscope 2, the analytical electron microscope 1 having the above two functions can be easily and inexpensively constructed. Become.

Further, the target 1 is placed on the scanning electron microscope 2.
By incorporating the 0 and the collimator 11, a high-intensity micro focus of X-rays can be easily obtained. Therefore, the X-ray beam generated from the target 10 is extremely narrow, so that the X-ray utilization efficiency is extremely high as compared with the X-ray tube in the conventional X-ray fluorescence analyzer, and high-sensitivity analysis can be performed. Become like

Although not shown, a filter for improving the monochromaticity of the irradiated X-rays and blocking the electron beam is provided by:
It may be provided between the target 10 and the sample 9.

FIG. 3 is a view similar to FIG. 1, showing another example of the embodiment of the present invention. The same components as those in the above-described example are denoted by the same reference numerals, and a detailed description thereof will be omitted.

In the above-described example, the target 10 is arranged between the objective lens 8 of the scanning electron microscope 2 and the sample 9, but in the analysis microscope 1 of this example, the target 10 is arranged as shown in FIG.
As shown in FIG. 2, a scanning analytical electron microscope 2 'is used, and a metal thin film target 10 is provided with a condenser lens 7 and an objective lens 8 of the scanning analytical electron microscope 2'.
Are provided movably at an image forming point in the middle between them as in the above-mentioned example. Another configuration of the analytical electron microscope 1 of this example is as follows.
This is the same as the previous example.

In the analytical electron microscope 1 of this embodiment thus configured, when the target 10 is inserted at an image forming point between the condenser lens 7 and the objective lens 8, that is, at the use position, the electron beam is The target 10 is irradiated to generate X-rays from the target 10, and the X-ray is irradiated to the sample 9 to set a fluorescent X-ray analyzer mode for analyzing the fluorescent X-rays generated from the sample 9. When the sample 10 is removed from the image forming point, that is, set at the non-use position, the characteristic X-ray generated from the sample 9 is analyzed by irradiating the sample 9 with an electron beam so as to focus on the sample 9. The scanning analytical electron microscope mode is set.

In this case, since the target 10 is inserted at an intermediate image point between the condenser lens 7 and the objective lens 8, the target 10 is inserted between the objective lens 8 and the sample 9 as in the above-described example. The working distance of the scanning analytical electron microscope 2 'is not limited as compared with the case where the scanning is performed. Thereby, the working distance is shortened, and high resolution is obtained in the scanning electron microscope mode of the analysis electron microscope 1.

Further, since the target 10 is inserted into the image forming point of the condenser lens 7, it is not necessary to change the excitation condition of the objective lens 8 in the fluorescent X-ray analyzer mode and the scanning analytical electron microscope mode. Thereby, the operation at the time of switching between the two modes becomes easier.

Further, when the target 10 is inserted at the image forming point of the condenser lens 7, the irradiation current of the electron beam is smaller than when the target 10 is inserted below the objective lens 8 as in the above-described example. Will be able to take large. As a result, the amount of X-rays generated on the target 10 increases.

[0034]

As is apparent from the above description, according to the analytical electron microscope of the first aspect of the present invention, an apparatus having both the function of an electron microscope and the function of an X-ray fluorescence analyzer is constituted. be able to. Therefore, by switching these two functions appropriately according to the analysis target and purpose,
Analysis under optimal conditions can be performed. Moreover, just by setting the target on the conventional electron microscope,
An analytical electron microscope having both functions can be easily and inexpensively constructed.

According to the second aspect of the present invention, since the X-rays for irradiating the sample are limited by the collimator, it is possible to easily obtain a fine focus of the X-rays with higher brightness. Therefore, since the X-ray beam from the target can be made extremely thin, the use efficiency of X-rays can be greatly improved as compared with the X-ray tube in the conventional fluorescent X-ray analyzer, and high-sensitivity analysis can be performed. become able to.

Further, according to the third aspect of the present invention, since the electron beam generator side and the sample side are hermetically shut off by the target support member, the electron beam generator side is maintained at a high vacuum. It is possible to set the sample side to the atmosphere or the helium atmosphere while keeping the state.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an example of an embodiment of an analytical electron microscope according to the present invention.

FIG. 2 is a detailed enlarged view of a portion II in FIG.

FIG. 3 is a diagram schematically showing another example of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Analysis electron microscope, 2 ... Scanning electron microscope, 3 ... X-ray detector, 4 ... Casing, 5 ... Electron gun, 6 ... Anode, 7 ...
Condenser lens, 8 ... objective lens, 9 ... sample, 10 ...
Target, 11: Collimator, 12: Support member, 13
... Seal member

Claims (4)

[Claims] An electron gun that emits an electron beam, a lens that converges the electron beam, and a sample support that is disposed below the lens on the central axis of the electron gun and supports a sample in a casing. And an X-ray detector for detecting X-rays generated from the sample in the casing, wherein the target is the central axis between the lens and the sample support. The target is disposed movably between a use position on a line and a non-use position deviated from the central axis, and the electron beam irradiates the target when the target is set at the use position. X-rays emitted from the sample irradiate the sample, and a fluorescent X-ray analyzer mode in which the X-ray detector detects fluorescent X-rays generated from the sample, and the target is set at the unused position. When, analytical electron microscope, wherein said electron beam is an electron microscope mode for detecting the characteristic X-rays generated from the sample by irradiating the sample with the X-ray detector is set. 2. When a plurality of the lenses are provided,
The analytical electron microscope according to claim 1, wherein the target is provided between the lenses. 3. The analysis according to claim 1, further comprising a collimator, which is located on the central axis and restricts X-rays, at a position closer to the sample support than a use position of the target. electronic microscope. 4. The target is fixedly supported by a support member movably provided on the casing, and the support member is configured such that when the target is located at a use position, the electron beam generator side and the sample Airtightly shut off the side
4. The analysis electron device according to claim 1, wherein a valve is provided for communicating the electron beam generator side and the sample side when the target is located at a non-use position. microscope.