JP3729341B2 - X-ray fluorescence analyzer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluorescent X-ray analyzer, and more particularly to a fluorescent X-ray analyzer provided with a plurality of excitation X-ray sources.
[0002]
[Prior art]
A fluorescent X-ray analyzer analyzes a constituent element, an internal structure, and the like of a sample based on fluorescent X-rays generated from the sample by irradiating primary X-rays. For example, a local material in the field of semiconductors and storage It can be applied to analysis, analysis of defective parts, and analysis of the chemical state of the cell surface in the biological field.
The fluorescent X-ray has a wavelength peculiar to the element, and the fluorescent X-ray analysis performs element characteristic analysis and quantitative analysis by measuring the wavelength and intensity of the fluorescent X-ray. In this fluorescent X-ray analysis, the wavelength of X-rays irradiated is varied according to the weight of the element to be measured.
[0003]
When measuring a wide range of elements, use a direct excitation source that directly irradiates the sample with the continuous X-rays generated from the X-ray tube and the characteristic X-rays directly as primary X-rays. In the case of measuring with high sensitivity, a monochrome excitation source in which a part of X-rays from the X-ray tube is converted into monochrome is used. In some cases, a direct excitation source may be used by switching X-ray tubes of a plurality of targets according to the measurement element.
Conventional fluorescent X-ray analyzers are equipped with multiple direct excitation sources or monochrome excitation sources in a single device, and switching between these excitation X-ray sources enables a wide range of analysis from light elements to heavy elements. Is known.
[0004]
[Problems to be solved by the invention]
In fluorescent X-ray analysis, it is necessary to observe the sample surface and determine an analysis position for irradiating X-rays, and accurately irradiate primary X-rays to the analysis position. At this time, in order to accurately irradiate the analysis position on the sample surface with the primary X-ray, the origin position on the sample stage and the X-ray irradiation position need to match.
If the primary X-ray irradiated by the fluorescent X-ray analyzer has a relatively large diameter of 1 mm or more, even if there is a deviation between the origin position on the sample stage and the X-ray irradiation center position. Since the irradiation diameter of the primary X-ray is sufficiently large, the origin position on the sample stage is included in the irradiation diameter of the primary X-ray, and the primary X-ray having sufficient intensity can be irradiated to the analysis position.
[0005]
On the other hand, high spatial resolution of 100 μm or less is required in the field of semiconductors and storage or in the biological field. In such a fluorescent X-ray analyzer that requires high spatial resolution, the primary X-ray irradiation diameter is also required to be 100 μm or less. In order to reduce the irradiation diameter to 100 μm or less, in the case of continuous X-rays, it is provided with a configuration comprising a plurality of polycapillaries, X-ray conduits or pinhole collimators, and in the case of characteristic primary X-rays, a double-curved spectral crystal is provided. It has a configuration.
[0006]
When the irradiation diameter of the primary X-ray is 100 μm or less, if there is a deviation between the origin position on the sample stage and the position of the X-ray irradiation center, the primary X-ray having sufficient intensity at the analysis position. Can not be irradiated. Therefore, in order to make the origin position on the sample stage coincide with the position of the X-ray irradiation center, it is necessary to sufficiently adjust the position of the excitation X-ray source.
[0007]
In general, in addition to an excitation X-ray source, an optical system such as a detector for detecting fluorescent X-rays or a CCD camera is disposed in the vicinity of a narrow space near the irradiation position of the fluorescent X-ray analyzer. In such a configuration, a plurality of excitation X-ray sources having a mechanism such as a plurality of polycapillaries, an X-ray conduit or a pinhole collimator, or a double curved spectral crystal for reducing the irradiation diameter to 100 μm or less are arranged, and It is difficult to adjust the position of the plurality of excitation X-ray sources in units of 100 μm or less.
Therefore, an X-ray fluorescence analyzer that includes an excitation X-ray source that irradiates continuous X-rays in a wide wavelength range and a plurality of excitation X-ray sources that irradiate characteristic X-rays in one apparatus is irradiated with primary X-rays. When the diameter of the primary X-ray is limited to a relatively large diameter of 1 mm or more and the diameter of the primary X-ray is 100 μm or less, an excitation X-ray source that emits continuous X-rays in a wide wavelength range, or one characteristic X An excitation X-ray source for irradiating a beam is provided.
[0008]
Therefore, in the X-ray fluorescence analysis that requires analysis of a minute part of 100 μm or less, there is a problem that it is necessary to prepare a plurality of X-ray fluorescence analyzers in order to analyze heavy elements from light elements. Therefore, there is a demand for a fluorescent X-ray analyzer capable of analyzing heavy elements from light elements in a minute portion of 100 μm or less. Further, there is a need for an X-ray fluorescence analyzer that facilitates alignment of the irradiation position on the sample surface when measuring a minute portion of 100 μm or less with a plurality of excitation X-rays.
[0009]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described conventional problems and facilitate the minute alignment of the irradiation positions of a plurality of excitation X-rays on the sample surface. It is another object of the present invention to analyze heavy elements from light elements with respect to a minute part of 100 μm or less with one fluorescent X-ray analyzer.
[0010]
[Means for Solving the Problems]
According to the present invention, for a plurality of excitation X-ray sources, a positional deviation between the irradiation position and the origin of the sample stage is stored as an offset amount, and the position of the offset amount is individually corrected, whereby a plurality of excitation X-ray sources Fine alignment of the irradiation position on the sample surface is facilitated, and it is possible to analyze heavy elements from light elements in a minute part of 100 μm or less with one fluorescent X-ray analyzer.
[0011]
The X-ray fluorescence analyzer of the present invention includes at least two excitation X-ray sources and a sample stage, and the sample stage has an irradiation position on the sample surface of the primary X-ray irradiated by each excitation X-ray source and a sample stage. The offset amount with respect to the origin is corrected for each excitation X-ray source. The offset amount corresponds to the excitation X-ray source used at the time of measuring and storing in advance the positional deviation between the irradiation position of the primary X-ray on the sample surface and the origin of the sample stage for each excitation X-ray source. The offset amount is read out, and the position of the sample stage is corrected using the offset amount so that the irradiation position matches the origin of the sample stage.
[0012]
The present invention relates to a direct excitation source for irradiating primary X-rays including continuous X-rays and characteristic X-rays generated from an X-ray tube, and characteristics obtained by making a part of primary X-rays generated from an X-ray tube monochrome (monochrome). Using a monochrome excitation source that irradiates X-rays, and constructing an excitation X-ray source by combining this direct excitation source or monochrome excitation source, or a combination of direct excitation sources and monochrome excitation sources with different targets. Can do.
[0013]
The direct excitation source irradiates primary X-rays including continuous X-rays and characteristic X-rays emitted from an X-ray tube with a plurality of X-ray conduits (polycapillary) or a pinhole collimator with an irradiation diameter of, for example, 100 μm or less. In addition, the monochromatic excitation source irradiates the primary X-rays from the X-ray tube after being converged to an irradiation diameter of, for example, 100 μm or less after being monochromated with a double curved spectral crystal.
The excitation X-rays irradiated from the respective excitation X-ray sources are irradiated to the same position of the sample by correcting the offset amount set for each with the sample stage.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view for explaining the outline of the fluorescent X-ray analyzer of the present invention. The X-ray fluorescence analyzer 1 generates primary X-rays and emits X-rays emitted from the sample S excited by the primary X-rays 2 and 3, which are irradiated on the sample S arranged on the sample stage 10. A detection unit 4 for detecting and measuring secondary X-rays such as an energy dispersive (EDX) X-ray detector, a measurement unit 16, and an imaging means such as a CCD camera for optically observing the sample S The optical observation means 5, the display means 15 for displaying the measurement result of the measurement unit 16 and the image by the optical observation means 5, the sample stage 10 that supports the sample S and determines the irradiation position of the excitation X-ray and the position control of the sample stage 10. The sample stage control means 11 to perform is provided.
[0015]
The excitation X-ray source includes a first excitation X-ray source 2 that irradiates continuous X-rays including a predetermined wavelength region, and a second excitation X-ray source 3 that irradiates monicized characteristic primary X-rays. The X-ray source 3 includes one or a plurality of excitation X-ray sources 3a and 3b. The first excitation X-ray source 2 and the second excitation X-ray source 3 select any one of the excitation X-rays and irradiate the sample S.
[0016]
The X-ray fluorescence analyzer 1 further includes an offset amount measuring unit 13 and an offset amount storage unit 14 in order to correct a positional deviation between the primary X-ray irradiation position and the origin of the sample stage 10. The offset amount measuring means 13 and the offset amount storage means 14 obtain and store in advance the positional deviation between the irradiation position of the primary X-ray on the sample surface and the origin of the sample stage for each excitation X-ray source, and control the sample stage. The means 11 reads the offset amount corresponding to the excitation X-ray source used at the time of measurement from the offset amount storage means 14, and uses the read offset amount so that the irradiation position and the origin of the sample stage coincide with each other. Perform position correction.
[0017]
The fluorescent X-ray analysis apparatus 1 includes a control unit 12, a switching control of the first excitation X-ray source 2 and the plurality of second excitation X-ray sources 3, an offset amount reading and writing control of the offset amount storage unit 14, The driving control of the sample stage control unit 11, the measurement control of the detector 4 and the measurement unit 16, the measurement control of the offset amount measurement unit 13, and the like are comprehensively controlled.
A configuration example of the first excitation X-ray source 2 and the second excitation X-ray source 3 will be described with reference to FIG. The first excitation X-ray source 2 includes an X-ray tube 21 such as an Rh target X-ray tube, and optical means 22 such as a plurality of polycapillaries, X-ray conduits, or a pinhole collimator. The X-ray conduit or polycapillary is an optical means for condensing X-rays, and the pinhole collimator is an optical means for limiting the primary X-ray irradiation diameter.
[0018]
The optical means 22 sets the primary X-ray generated by the X-ray tube 21 to an irradiation diameter of 30 to 50 μm on the sample S. Although the irradiation diameter varies depending on the wavelength, the first excitation X-ray source 2 of the present invention is focused and irradiated so as to have an irradiation diameter of 100 μm or less. Excitation X-rays from the first excitation X-ray source 2 have substantially the same wavelength distribution as primary X-rays from the Rh target X-ray tube, and can be applied in a wide range from heavy elements to light elements. The light element can be applied to an element having an atomic number smaller than that of Ti.
[0019]
The second excitation X-ray source 3 includes an X-ray tube 31 such as a Mo target X-ray tube, and a double curved spectral crystal 32 such as Mica. The double-curved spectroscopic crystal 32 converts the specific wavelength (Mo-Kα in the case of Mo target X-ray tube) in the primary X-ray from the X-ray tube 31 into a monochrome and converges on the sample surface with a diameter of, for example, about 40 μm. And then irradiate. According to the excitation X-ray obtained by making the primary X-ray from the Mo target X-ray tube monochrome, in the X-ray fluorescence analysis of the heavy element region from Cu to Ti, the background is reduced and the analysis is performed with high sensitivity. Can do.
The second excitation X-ray source 3 can include a plurality of excitation X-ray sources 3a and 3b having different wavelengths of the excitation X-rays, and selectively select excitation X-rays having a predetermined wavelength under the control of the control means 12. Can be irradiated. In FIG. 2, only one second excitation X-ray source 3 is shown.
[0020]
The fluorescent X-ray analyzer 1 according to the present invention is a means for correcting each positional deviation between the irradiation position of the excitation X-rays irradiated by each excitation X-ray source and the origin position of the sample stage, and the origin position of the sample stage. Offset amount measuring means 13 for measuring the offset amount, offset amount storing means 14 for storing the measured offset amount, and sample stage control means 11 for controlling the position of the sample stage 10 using this offset amount.
[0021]
Hereinafter, the procedure for measuring the offset amount will be described using the flowchart of FIG. 3, and the procedure for correcting the offset amount will be described using the flowchart of FIG. FIG. 4 is a diagram for explaining the offset amount between the excitation X-ray irradiation position and the center position of the sample stage.
In the flowchart of FIG. 3, the offset amount is measured by measuring the positional deviation between the irradiation position and the origin of the sample stage for each excitation X-ray source. First, an excitation X-ray source for measuring an offset amount is selected from the first excitation X-ray source 2 and a plurality or one second excitation X-ray source 3 (step S1). After arranging the fluorescent screen on the sample stage (step S2), the primary X-rays of the selected excitation X-ray source are irradiated onto the fluorescent screen. The fluorescent plate generates fluorescence by the irradiated primary X-ray, and the irradiation position of the primary X-ray can be known from the light emission position (step S3).
[0022]
The light emitting point on the fluorescent screen is imaged by an imaging means such as a CCD camera provided in the optical observation means 5. At this time, the center position of the optical observation means 5 and the origin of the sample stage 10 are aligned in advance. By this alignment, a positional deviation between the irradiation position and the origin of the sample stage 10 can be obtained by a positional deviation between the irradiation position and the center position of the optical observation means 5. The image of the optical observation means 5 can be displayed on the display means 15. FIG. 4 schematically shows an example of an image obtained by the optical observation means 5, where O indicates the center position of the observation image and P indicates the irradiation position of the primary X-ray. Δx and Δy indicate the offset amount of the irradiation position P of the primary X-ray with respect to the center position O. By making the center position O of the observation image coincide with the center position of the sample stage in advance, the offset amounts Δx and Δy become the offset amount of the primary X-ray irradiation position with respect to the origin of the sample stage (step S4).
[0023]
The offset amount measuring means 13 measures the amount of positional deviation between this irradiation position and the center position of the sample stage 10 as an offset amount. The offset amount is measured by aligning the center position of the sample stage 10 with the irradiation position while observing the image of the optical observation means 5 (step S5). In addition to obtaining the amount of movement of the sample stage 10 at this time, The positional deviation from the center position of the optical observation means 5 can be obtained by measuring from the image data (step S6). The measured offset amount is stored in the offset amount storage means 14 (step S7).
Steps S1 to S7 are performed on the excitation X-ray source included in the fluorescent X-ray analyzer 1 (step S8). Thereby, the offset amounts of the respective excitation X-ray sources 2 and 3 can be stored.
[0024]
Next, the offset amount correction procedure will be described with reference to the flowchart of FIG. The control unit 12 selects an excitation X-ray source that generates excitation X-rays corresponding to the target element measurement (step S11), reads an offset amount corresponding to the selected excitation X-ray source from the offset amount storage unit 14, The sample is sent to the sample stage control means 11 (step S12). The sample stage control means 11 corrects the position of the sample stage 10 using the offset amount (step S13), and irradiates the sample S with excitation X-rays from the excitation X-ray source. Since the sample stage 10 is offset-corrected, the irradiated excitation X-rays are irradiated to the origin of the sample stage (step S14). The fluorescent X-rays generated from the sample by the irradiation of the excited X-rays are detected by the detector, and the fluorescent X-ray measurement is performed (step S15).
[0025]
According to the present invention, even when the excitation X-ray source is switched, the irradiation position of the excitation X-ray from each excitation X-ray source and the origin of the sample stage can be made coincident with each other. X-rays can be irradiated.
Further, according to the present invention, in the fluorescent X-ray analysis apparatus, even when the irradiation position is shifted from the origin of the sample stage due to the manufacturing error or assembly error of each part, each excitation X-ray source is installed. The offset amount can be corrected without adjusting the position.
[0026]
In particular, in a configuration including a plurality of excitation X-ray sources in a narrow space, it is difficult to adjust the installation position. However, according to the present invention, the offset amount can be corrected by driving the sample stage. The present invention can also be applied to a configuration including a plurality of excitation X-ray sources.
[0027]
【The invention's effect】
As described above, according to the fluorescent X-ray analysis apparatus of the present invention, it is possible to facilitate fine alignment of the irradiation positions on the sample surface of a plurality of excitation X-rays. Moreover, heavy elements can be analyzed from light elements with respect to a minute part of 100 μm or less by one fluorescent X-ray analyzer.
[Brief description of the drawings]
FIG. 1 is a schematic view for explaining the outline of a fluorescent X-ray analysis apparatus of the present invention.
FIG. 2 is a diagram for explaining a configuration example of a first excitation X-ray source and a second excitation X-ray source according to the present invention.
FIG. 3 is a flowchart for explaining a procedure for measuring an offset amount by the X-ray fluorescence analyzer of the present invention.
FIG. 4 is a diagram for explaining an offset amount between an irradiation position of excitation X-rays and a center position of a sample stage.
FIG. 5 is a flowchart for explaining a procedure for correcting an offset amount by the X-ray fluorescence analyzer of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... X-ray fluorescence analyzer, 2 ... 1st excitation X-ray source, 3, 3a, 3b ... 2nd excitation X-ray source, 4 ... Detector, 5 ... Optical observation means, 11 ... Sample stage control means, 12 ... Control means, 13 ... offset amount measuring means, 14 ... offset amount storage means, 15 ... display means, 16 ... measuring means, O ... origin, P ... irradiation position, S ... sample.

Claims (2)

Comprising at least two excitation X-ray sources and a sample stage;
The sample stage is a fluorescent X-ray analyzer that corrects the position of the offset of the irradiation position on the sample surface of the primary X-ray irradiated by each excitation X-ray source and the origin of the sample stage for each excitation X-ray source. . 2. The fluorescent X-ray analyzer according to claim 1, wherein the irradiation diameter of the primary X-rays irradiated by the excitation X-ray source does not exceed 100 μm.

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