JP4715345B2 - X-ray analyzer - Google Patents

Description

  The present invention relates to an X-ray spectrometer, and more particularly, suitable for analyzing a micro area on a sample such as a transmission electron microscope (TEM), an electron beam probe microanalyzer (EPMA), a scanning electron microscope (SEM), and the like. The present invention relates to an X-ray analyzer.

  In an electron beam probe microanalyzer (EPMA), when a sample is irradiated with a minute diameter electron beam having a medium energy of about 20 to 30 keV as an excitation line, the inner electrons of the sample contained therein are excited. By analyzing the characteristic X-rays emitted to the outside (characteristic X-rays), the elements are identified and quantified, and the distribution of the elements is examined. In addition, the scanning electron microscope (SEM) generally detects secondary electrons and reflected electrons generated from the irradiation position of the electron beam, but recently, an X-ray analysis is performed by adding an energy dispersive X-ray detector. A device that enables this is also being developed.

  In this type of X-ray analyzer, it is necessary to efficiently disperse intrinsic X-rays emitted from a minute region that can be regarded as almost one point on a sample. Therefore, conventionally, an X-ray spectrometer having a configuration described in Patent Document 1 is known. 6 is a schematic configuration diagram of the X-ray spectrometer, FIG. 7 is an enlarged view of the incident side of the multi-capillary X-ray lens 3 in FIG. 6, and FIG. 8 is a diagram inside the single capillary 3a in the multi-capillary X-ray lens 3. It is a schematic diagram which shows the passage state of X-rays.

  As shown in FIG. 7, the multi-capillary (sometimes referred to as polycapillary) X-ray lens 3 has a large number of capillaries (several hundreds) made of borosilicate glass having a small diameter of about 2 to several tens μm, for example. (About 1 million pieces) The basic structure is bundled, and as shown in FIG. 8, the X-rays incident on the inside of one capillary 3a travel while totally reflecting the inner peripheral surface of the glass wall. The X-ray is efficiently guided by using the principle of the process (see Patent Documents 2 and 3). There are various types of multicapillary X-ray lenses, but what is used here is a large three-dimensional X-ray emitted from an X-ray source F which has a point focal point on the incident end face side and can be regarded as almost a point. It takes in with an angle and emits a parallel beam from the exit side end face.

  In FIG. 6, the multicapillary X-ray lens 3 is arranged so that the point focal point of the incident side end face comes to the minute region 2 on the sample 1, and thereby, the intrinsic X emitted from the minute region 2 by the electron beam irradiation. The line is efficiently taken into the multicapillary X-ray lens 3. The X-rays that have been converted into parallel light and emitted from the multicapillary X-ray lens 3 are introduced into the flat plate crystal 4 and reflected while being wavelength-dispersed, and this dispersed light is detected by the X-ray detector 6. In this configuration, when scanning the spectral wavelength, the flat plate crystal 4 is rotationally driven by an angle θ about the axis 5 perpendicular to the paper surface, and the X-ray detector 6 is also centered on the axis 5. Is rotated so as to maintain an angle 2θ that is twice the rotation angle θ.

  However, this configuration has the following problems. That is, as shown in FIG. 8A, inside each capillary 3a of the multi-capillary X-ray lens 3, the X-ray proceeds while being totally reflected at an angle equal to or less than the critical angle and reaches the emission side end face. For this reason, the X-rays emitted from the emission side end face of the multicapillary X-ray lens 3 are not strictly parallel light but have a maximum extent of a critical angle at the time of emission from the emission side end face. As described above, the X-rays enter the flat plate crystal 4 while spreading with a certain degree of opening angle, which is a cause of lowering the wavelength resolution.

  In the conventional configuration, the wavelength resolution is determined depending on the type of the plate spectral crystal 4 and the parallelism of the X-rays emitted from the multicapillary X-ray lens 3 as described above. In the analysis apparatus, there are cases where high wavelength resolution is required or not depending on the purpose of analysis. For example, in order to perform precise elemental analysis and chemical state analysis of a minute region of a sample, it is necessary to acquire a spectrum with high wavelength resolution, but when performing trace component analysis etc., not so high wavelength resolution is required. High detection sensitivity is required. Therefore, if the wavelength resolution can be arbitrarily set, more accurate analysis data can be collected according to the analysis purpose and the like.

JP 2004-294168 A Japanese Examined Patent Publication No. 7-11600 Japanese Patent Publication No. 7-40080 JP 10-232209 A

  The present invention has been made to solve the above-mentioned problems, and a first object of the present invention is to be emitted from a minute region on a sample in response to irradiation of an electron beam or the like focused to a minute diameter. An object of the present invention is to provide an X-ray analyzer capable of improving the wavelength resolution when spectrally analyzing X-rays.

  A second object of the present invention is to provide an X-ray analyzer which can set the wavelength resolution appropriately according to the user's request with a simple configuration.

The present invention made to solve the above-mentioned problems is an X-ray analyzer for spectroscopically analyzing X-rays emitted from a minute region that can be regarded as a substantially point on a sample,
a) a multicapillary X-ray lens having a point focal point on the incident end face side facing the sample and emitting substantially parallel light on the exit end face side;
b) an X-ray spectrometer that wavelength-disperses X-rays collimated by the multicapillary X-ray lens;
c) an X-ray detector for detecting X-rays dispersed by the X-ray spectrometer;
are arranged in a distributed after the X-ray beam path between the dispersion and before the X-ray beam path and the X-ray spectrometer and the X-ray detector between the d) the multi-capillary X-ray lens the X-ray spectrometer Solar slit,
It is characterized by having.

In X-ray analysis apparatus according to the present invention, the solar slits respectively disposed and distributed before X-ray beam path and a dispersion after the X-ray light path is, X-rays toward the X-ray spectrometer is emitted from the multi capillary X-ray lens And non-parallel components in the X-ray bundles diffracted by the X- ray spectrometer and directed to the X-ray detector are removed, and the parallelism is enhanced. As a result, the solar slit has a function of eliminating scattered rays that interfere with spectroscopic analysis and a function of improving wavelength resolution.

  Therefore, according to the X-ray analysis apparatus of the present invention, the influence of the spread of the X-rays emitted from the multicapillary X-ray lens that efficiently collects X-rays emitted from a minute region that can be regarded as a substantially point on the sample is reduced. The wavelength resolution can be improved as compared with the conventional X-ray analyzer.

  In addition, since the solar slit removes the incident X-rays by absorbing non-parallel components, the X-ray intensity is attenuated at least by that amount. As the slit opening angle of the slit is narrowed, the attenuation of the X-ray intensity increases and the analysis sensitivity is lowered. That is, in this case, since analysis sensitivity and wavelength resolution are in a trade-off relationship, it is not appropriate to use a solar slit with a narrow slit opening angle in order to increase the wavelength resolution more than necessary.

Therefore, as one embodiment of X-ray analysis apparatus according to the present invention, preferably, the solar slits arranged in the dispersion prior to X-ray light path及beauty min Chinochi X-ray beam path is a both a parallel plate structure The switching means for switching the slit opening angle of one solar slit may be further provided.

  Specifically, the switching means can be configured to selectively insert and retract on the X-ray optical path by mechanically moving a plurality of solar slits having different slit opening angles, for example. According to this configuration, for example, in order to obtain a spectrum in which wavelength resolution is given priority over analytical sensitivity in order to perform elemental analysis, chemical state analysis, etc., a solar slit with a relatively narrow slit opening angle is used. What is necessary is just to insert on an X-ray optical path. On the other hand, in order to give priority to analysis sensitivity over wavelength resolution in order to perform, for example, trace component analysis, a solar slit having a relatively wide slit opening angle may be inserted into the X-ray optical path.

  As described above, according to the X-ray analyzer having the above-described configuration, the user can set appropriate conditions in consideration of the balance between the wavelength resolution and the analysis sensitivity in accordance with the purpose of analysis and the type of sample. Thereby, accurate data according to the purpose of analysis can be obtained.

Further, to secure the slit opening angle of hand of the Soller slit, the slit opening angle of the other solar slit when a variable, the slit opening angle of the solar slits distributed after the X-ray beam path is fixed, prior to dispersion It is preferable that the slit opening angle of the solar slit on the X-ray optical path can be switched by the switching means. At this time, the slit opening angle of the solar slit on the X-ray optical path after dispersion is preferably fixed at a medium level.

  According to this configuration, when it is desired to increase the analysis sensitivity instead of lowering the wavelength resolution relatively, the slit opening angle of the solar slit is widened in front of the X-ray spectrometer and the attenuation of the X-ray intensity is suppressed. It is particularly advantageous for increasing the analytical sensitivity.

  Of course, contrary to the above configuration, the slit opening angle of the solar slit on the X-ray optical path before dispersion is fixed, and the slit opening angle of the solar slit on the X-ray optical path after dispersion can be switched by the switching means. I do not care.

  In addition, in the configuration in which the slit opening angle of the solar slit is switched, the spectral crystals of the X-ray spectrometer may be the same, but preferably, the X-ray spectrometer has a plurality of spectral crystals having different spectral characteristics and a crystal switching for switching between them. And switching the spectral crystal by the crystal switching means and switching the slit opening angle of the solar slit by the switching means.

  In this configuration, if you want to perform analysis that gives priority to analysis sensitivity over wavelength resolution, or conversely, if you want to perform analysis that gives priority to wavelength resolution over analysis sensitivity, the optimal spectroscopic crystal is selected and solar power is selected accordingly. Set the slit opening angle of the slit. Thereby, compared with the case where the same spectral crystal is used, the analysis sensitivity can be increased even with the same wavelength resolution.

  In the X-ray analysis apparatus according to the present invention, the solar slit on the X-ray optical path after dispersion can be integrated with the X-ray detector. According to this, since the solar slit is disposed in the immediate vicinity of the X-ray detector, the influence of scattered X-rays and the like can be more reliably removed. Further, since the relative position between the solar slit and the X-ray detector is determined, it is easy to perform operations such as assembly and position adjustment of the apparatus.

[Example 1]
An embodiment (Example 1) of the X-ray analyzer according to the present invention will be described. FIG. 1 is a schematic configuration diagram of an X-ray optical system of an X-ray analyzer according to this embodiment. The same components as those already described in FIG. 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the X-ray analyzer according to the first embodiment, a multicapillary X-ray lens 3 having a point focal point on the incident side end face in the vicinity of a minute region 2 on a sample 1 and a plate spectral crystal 4 which is an X-ray spectrometer in the present invention. A first solar slit 7 is inserted on the X-ray optical path before dispersion, and a second solar slit 8 is inserted on the X-ray optical path after dispersion between the plate spectral crystal 4 and the X-ray detector 6. The first solar slit 7 is fixed and integrated at the outlet of the multi-capillary X-ray lens 3, while the second solar slit 8 is fixed and integrated at the inlet of the X-ray detector 6. Each of the first and second solar slits 7 and 8 has a parallel plate structure in which a plurality of thin plates (slit plates) made of a material that absorbs X-rays, such as stainless steel, are stacked at a predetermined interval. Usually, the slit opening angle is determined by the opening width of the overlapping slit plates and the length in the X-ray passing direction.

  In the configuration of FIG. 1, an electron beam emitted from the electron gun 10 is irradiated to a minute region 2 on the sample 1 through a deflection coil 11 for position scanning. The intrinsic X-rays excited by the electron beam and emitted from the minute region 2 are efficiently collected by the multicapillary X-ray lens 3 and converted into parallel light. X-rays emitted from the multicapillary X-ray lens 3 are not completely parallel light but have a certain spread angle for the reasons described above, but are not parallel components when passing through the first solar slit 7. Is absorbed by the slit plate, X-rays with increased parallelism hit the flat plate crystal crystal 4 and are wavelength-dispersed. As a result, the variation in the wavelength of the X-rays reflected at a certain diffraction angle and traveling toward the X-ray detector 6 is reduced, that is, the spectral X-rays have a high wavelength resolution.

The spectral X-rays pass through the second solar slit 8 in front of the X-ray detector 6. At this time, scattered X-rays incident from a direction not parallel to the desired spectral X-rays are absorbed by the slit plate. . Therefore, such unnecessary X-rays are removed, the purity of the desired spectral X-rays is increased, reaches the X-ray detector 6, and is detected by the X-ray detector 6.
As described above, in the X-ray analysis apparatus having the configuration of the first embodiment, the wavelength resolution is improved by the action of the two solar slits 7 and 8 respectively inserted on the upper and lower sides of the flat plate crystal crystal 4.

First respectively to the upstream side and the downstream side of the upper Symbol Example flat dispersive crystal 4 is X-ray analysis apparatus according to 1, but equipped with a second solar slit 7 and 8 shown in FIG. 6 alone either Compared with the conventional configuration, the wavelength resolution can be improved. FIG. 2 is a schematic configuration diagram of an X-ray analyzer according to a reference example not included in the present invention. In this configuration, only on the X-ray optical path after dispersion between the flat plate crystal 4 and the X-ray detector 6. A solar slit 8 is provided. In this case, the X-ray having a certain extent emitted from the multicapillary X-ray lens 3 hits the plate spectral crystal 4, but the X-ray having the target wavelength among the spectral X-rays diffracted by the plate spectral crystal 4 Since the non-parallel X-rays are removed by the solar slit 8, the wavelength resolution can be improved.

[Example 2 ]
In the first embodiment , the wavelength resolution is fixed. On the other hand, in the following Examples 2 to 4, the wavelength resolution and the sensitivity in a trade-off relationship with this can be selected. FIG. 3 is a schematic configuration diagram of an X-ray optical system of the X-ray analyzer according to the second embodiment. In the X-ray analyzer according to the second embodiment, the first and second solar slits 7 and 8 are arranged in the pre-dispersion X-ray optical path and the post-dispersion X-ray optical path, respectively, as in the first embodiment. In both the first and second solar slits 7 and 8, two types of solar slits 7a and 7b (or 8a and 8b) having different slit opening angles can be switched by the switching mechanisms 10 and 11.

  Although various forms can be considered as the switching mechanisms 10 and 11, for example, a configuration in which one of two solar slits is selectively inserted into or retracted from the X-ray optical path by a linear slide movement mechanism, a rotation movement mechanism, or the like. The mechanism may be either manually operated by a user operating an operating body such as a knob, or automatically operated in response to a user switch operation using a driving mechanism such as a motor. But you can. The wider the slit opening angle of the solar slit, the worse the parallelism of the passing X-rays, and the wavelength resolution decreases. However, the attenuation of the passing X-rays decreases, so the intensity of the X-rays detected by the X-ray detector 6 is Increases sensitivity. Therefore, the user may select a solar slit having an appropriate slit opening angle with each of the solar slits 7 and 8 by performing a predetermined operation in accordance with the purpose of analysis, and execute spectral analysis under the selection conditions.

[Example 3 ]
FIG. 4 is a schematic configuration diagram of an X-ray optical system of the X-ray analyzer according to the third embodiment. In the X-ray analyzer of Example 3 , only the first solar slit 7 arranged on the X-ray optical path before dispersion can be changed in slit opening angle, and the second solar slit 8 arranged on the X-ray optical path after dispersion is slit. The opening angle is fixed. In this case, the slit opening angle of the second solar slit 8 is determined to be relatively larger than the slit opening angle of the first solar slit 7, and the two solar slits 7a having different slit opening angles in the first solar slit 7 are determined. , 7b can be selected as appropriate to determine the wavelength resolution and sensitivity.

  In contrast to the configuration of FIG. 4, the slit opening angle of the first solar slit 7 may be fixed and the slit opening angle of the second solar slit 8 may be variable. However, if the X-ray intensity is attenuated to some extent in the pre-dispersion X-ray optical path, the adjustment range of the X-ray intensity by changing the slit opening angle of the second solar slit 8 becomes small, which is disadvantageous for increasing the analysis sensitivity. It is. Therefore, adjusting the attenuation of the X-ray intensity on the pre-dispersion X-ray optical path as in the configuration of FIG. 4 is advantageous in increasing the analysis sensitivity.

[Example 4 ]
FIG. 5 is a schematic configuration diagram of an X-ray optical system of the X-ray analyzer according to the fourth embodiment. The X-ray analysis apparatus of this Example 4 is provided with solar slits 7 and 8 with variable slit opening angles on the pre-dispersion X-ray optical path and the post-dispersion X-ray optical path as in Example 2 . The second two points are different from the second embodiment. That is, one of them is that a plurality of (here, four) flat plate spectral crystals 42, 43, 44, 45 having different spectral characteristics mounted on the holder 41 can be switched by the switching mechanism 12. is there. As the spectral crystal, for example, LSA (artificial multilayer film), PbST (lead stearate), LIF, ADP, RAP, PET, or the like can be used. For example, LSA and PbST that split the same wavelength region have different wavelength resolution, and the latter has higher wavelength resolution. Another difference from the second embodiment is that the X-ray detectors 6a and 6b having different detection characteristics are provided for the solar slits 8a and 8b having different slit opening angles in the second solar slit 8. It is that you are. For example, a gas flow type proportional counter as the X-ray detector 6b corresponding to the solar slit 8b having a relatively wide slit opening angle, and a gas as the X-ray detector 6a corresponding to the solar slit 8a having a relatively narrow slit opening angle. An encapsulated proportional counter is used.

  The user selects a spectral crystal having an appropriate spectral characteristic by the switching mechanism 12 according to the purpose of analysis, and sets it at a position where X-rays coming from the multi-capillary X-ray lens 3 are hit, and matches the characteristic of the spectral crystal. A slit opening angle is selected for each of the solar slits 7 and 8. Thereby, spectral analysis utilizing the spectral characteristics of each spectral crystal can be performed, and the analysis sensitivity can be ensured as much as possible while further improving the wavelength resolution as compared with the configuration of the third embodiment.

s
Since the above embodiment is an example of the present invention, it will be understood that it is included in the claims of the present application even if it is appropriately changed, modified or added within the scope of the present invention.
For example, in FIGS. 1 to 5 corresponding to the first to fifth embodiments, the multicapillary X-ray lens 3 is drawn in a substantially linear form, but the multicapillary X-ray lens 3 can be curved due to its characteristics. Therefore, the position of the plate spectral crystal 4 with respect to the sample 1 can be determined fairly freely.

1 is a schematic configuration diagram of an X-ray optical system of an X-ray analyzer according to an embodiment of the present invention. The schematic block diagram of the X-ray optical system of the X-ray analyzer which is a reference example which is not contained in this invention. The schematic block diagram of the X-ray optical system of EMPA which is the other Example of this invention. The schematic block diagram of the X-ray optical system of EMPA which is the other Example of this invention. The schematic block diagram of the X-ray optical system of EMPA which is the other Example of this invention. 1 is a schematic configuration diagram of a conventional EMPA X-ray optical system. The enlarged view of the entrance side of the multicapillary X-ray lens in FIG. The schematic diagram which shows the passage state of the X-ray in one capillary in a multicapillary X-ray lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sample 10 ... Electron gun 11 ... Deflection coils 20, 21, 22 ... Switching mechanism 2 ... Micro area 3 ... Multicapillary X-ray lens 4, 42, 43, 44, 45 ... Flat plate crystal 41 ... Holder 6, 6a, 6b: X-ray detectors 7, 7a, 7b, 8, 8a, 8b ... Solar slits

Claims (5)

An X-ray analyzer for spectroscopically analyzing X-rays emitted from a minute region that can be regarded as an almost point on a sample,
a) a multicapillary X-ray lens having a point focal point on the incident end face side facing the sample and emitting substantially parallel light on the exit end face side;
b) an X-ray spectrometer that wavelength-disperses X-rays collimated by the multicapillary X-ray lens;
c) an X-ray detector for detecting X-rays dispersed by the X-ray spectrometer;
are arranged in a distributed after the X-ray beam path between the dispersion and before the X-ray beam path and the X-ray spectrometer and the X-ray detector between the d) the multi-capillary X-ray lens the X-ray spectrometer Solar slit,
An X-ray analysis apparatus comprising: The solar slits arranged on the pre-dispersion X-ray optical path and the post-dispersion X-ray optical path both have a parallel plate structure, and the slit opening angle of the solar slit on the post-dispersion X-ray optical path is fixed, and before the dispersion X-ray analysis apparatus according to claim 1, characterized in that a switchable by the switching Rikae means a slit opening angle of Soller slit X-ray optical path. The solar slits arranged on the pre-dispersion X-ray optical path and the post-dispersion X-ray optical path both have a parallel plate structure, and the slit opening angle of the solar slit on the pre-dispersion X-ray optical path is fixed, and after the dispersion X-ray analysis apparatus according to claim 1, characterized in that a switchable by the switching Rikae means a slit opening angle of Soller slit X-ray optical path. The X-ray spectrometer includes a plurality of spectral crystals having different spectral characteristics and crystal switching means for switching between them, and switching of the spectral crystal by the crystal switching means and switching of the slit opening angle of the solar slit by the switching means. 4. The X-ray analysis apparatus according to claim 2, wherein the X-ray analysis apparatus can be associated with each other. X-ray analysis apparatus according to any one of claims 1-4 Soller slit of the dispersion after the X-ray beam path is characterized in that it is integrated with the X-ray detector.

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