JP2011095224A - Dispersive crystal, wavelength dispersion type x-ray analysis device, and element distribution measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersive crystal 13, an wavelength dispersion type X-ray analysis device 10, and an element distribution measuring method, efficiently detecting more elements simultaneously and improving the energy resolution of a spectrum. <P>SOLUTION: The dispersive crystal 13 includes an inside surface forming a shape with lined arcs perpendicular to a reference plane surface including a predetermined reference line. The inside surface is constructed so that a curvature radius of an arc may decrease from a sample 1 to a detector 14 along the reference line and an angle formed by a line segment and a reference line from a reference intersection to the sample 1 side may decrease, which connects an arc intersection at which an arc and a reference plane intersect and a reference intersection at which the reference line and a plane including an arc intersect. The dispersive crystal 13 is arranged so that the reference line may agree with an axis connecting the sample 1 and the detection part 14. The detector 14 includes a linear or planar detection part 14a detecting an X-ray which is arranged to be perpendicular to an axis that the detection part 14a connects the sample 1 and the detector 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a spectral crystal, a wavelength dispersive X-ray analyzer, and an element distribution measuring method.

  Fluorescent X-rays or characteristic X-rays generated by irradiating a sample with X-rays or electron beams have unique wavelengths depending on the respective elements. Therefore, it is possible to analyze the elements constituting the sample by measuring them. it can.

  An apparatus using X-rays as a probe is called an X-ray fluorescence analyzer (XFA). In many cases, a scanning electron microscope (SEM) and an electron probe micro analyzer (EPMA) are also provided with a device for analyzing characteristic X-rays generated by electron beam excitation. . These fluorescent X-ray and characteristic X-ray analyzers are largely classified into an energy dispersion type and a wavelength dispersion type.

  The energy dispersive type using a semiconductor detector has the advantage of being able to detect fluorescent X-rays and characteristic X-rays efficiently with a wide solid angle. However, since the energy resolution is about 150 eV, the detection limit of analysis concentration is 0.1 at%. There are problems such as high and low, and fluorescence / characteristic X-rays that are close in wavelength cannot be sufficiently separated.

  On the other hand, the wavelength dispersion type has an energy resolution of about 10 eV, which is significantly superior to the energy dispersion type. Therefore, the detection lower limit is improved by one to two digits due to the relationship between the signal / background ratio. Further, since the peaks of fluorescence and characteristic X-rays do not overlap, quantitative analysis is easy. Furthermore, detailed spectral analysis enables not only elemental analysis but also evaluation of chemical state.

  As shown in FIG. 10, a conventional wavelength dispersive X-ray fluorescence analyzer irradiates a wide area of a sample with X-rays from an X-ray generation source to excite and emits the emitted X-ray fluorescence to a solar slit. In general, the light is passed through and is subjected to Bragg reflection by a flat plate crystal crystal, and then detected by an X-ray detector such as a scintillation counter. In this method, a fluorescent X-ray spectrum is acquired by scanning while maintaining the angle relationship of θ-2θ of the sample, the flat plate crystal, and the detector (see, for example, Non-Patent Document 1).

  Further, wavelength dispersion type analyzers in SEM and EPMA analyze characteristic X-rays generated from a region of several hundred microns or less in diameter by a focused electron beam. As shown in FIG. 11, characteristic X-rays are condensed on the light receiving surface of the X-ray detector by Bragg reflection of a curved crystal called Johann or Johansson type. The X-ray generation source, the Johansson-type curved crystal, and the light-receiving surface of the X-ray detector are arranged on a circumference called a Roland circle, and a spectrum is acquired by precise angular scanning that maintains the relationship of θ-2θ. . This method is generally called a concentrated method, and is characterized in that it can be analyzed efficiently by receiving characteristic X-rays or fluorescent X-rays at a wide solid angle and performing Bragg reflection (see, for example, Non-Patent Document 2 or 3). Further, even in the case of X-ray excitation, it can be applied if the primary X-ray is appropriately focused by the slit and the fluorescent X-ray source is limited to a minute region.

  However, in the conventional wavelength dispersion type X-ray analyzers as described in Non-Patent Documents 1, 2, and 3, the X-2 of the fluorescent X-ray / characteristic X-ray generation source, the spectral crystal, and the X-ray detector There is a problem that a long measurement time is required because it is necessary to perform precise angular scanning while maintaining the angular relationship. In addition, there is a problem that the sample may be damaged because it is necessary to continue irradiation with a high-power electron beam.

  In order to solve such problems, non-scanning wavelength dispersion X-ray analysis has been proposed which has a short measurement time and little sample damage. As shown in FIG. 12, fluorescent X-rays from a minute X-ray generation source are Bragg-reflected by a plate spectral crystal, and a fluorescence X-ray diffraction pattern is measured by a two-dimensional detector. There is an experiment in which an X-ray spectrum is obtained with an energy resolution of 2.4 eV (for example, see Non-Patent Document 4). In this method, since fluorescent X-rays and characteristic X-rays cannot be collected, a two-dimensional detector is required for their measurement. Moreover, since it is a flat plate crystal, it is difficult to receive fluorescent X-rays and characteristic X-rays with a large solid angle. In addition, fluorescent X-rays and characteristic X-rays after Bragg reflection by the spectroscopic crystal travel with an angular spread, so if the area of the two-dimensional detector is small, the detectable wavelength range becomes narrow. There are difficulties in terms of efficiency.

  Therefore, the present inventors used X-rays or electron beams that were controlled or restricted so that the length of the side of the beam in the direction parallel to the axis connecting “sample”-“detector” converged to 300 μm or less. Irradiation and fluorescent X-rays or characteristic X-rays generated from the sample are different for each wavelength by using a diffraction phenomenon of a cylindrical curvature distribution crystal lens whose crystal direction is controlled perpendicular to the cylindrical crystal surface. Non-scanning type that can measure fluorescent X-rays or characteristic X-ray spectra in a wide wavelength range at a time by focusing on the position and detecting them with a two-dimensional or one-dimensional position sensitive X-ray detector A wavelength dispersive X-ray analyzer has been proposed (see, for example, Patent Document 1). In addition, as shown in FIG. 13, in the field of plasma-excited X-ray emission, there is an example in which a conical crystal is produced and a spectroscopic experiment is performed using a two-dimensional X-ray detector (for example, non-existing). (See Patent Document 5).

  In addition, the cylindrical curvature distribution crystal lens shown in Patent Document 1 is obtained by plastically processing a single crystal plate such as Si, Ge, SiGe or the like at a temperature near the melting point of the crystal by high-temperature pressurization, and molding it into a cylindrical shape. (See, for example, Non-Patent Document 6) The crystal orientation is controlled with an accuracy of at least 0.1 degrees or less perpendicular to the ideal cylindrical surface. In addition, the present inventors have developed reverse X-ray photoelectron holography, which is a three-dimensional atomic imaging technique around a specific element (see, for example, Patent Document 2). This inverse X-ray photoelectron holography can, for example, determine the environmental structure of dopants in semiconductors and adsorbates on the surface in three dimensions, and is expected to make a significant contribution to the elucidation of the physical properties and functions of various substances and materials. It is an innovative evaluation method.

JP 2008-180656 A JP 2006-300558 A

Yoichi Koshi, Kimitaka Sato, "Frontier of X-ray analysis", Agne Technical Center, 1998 Japan Surface Science Society, "Electron Probe Microanalyzer", Maruzen Co., Ltd., 1999 Kenji Sakurai, “Development of an ultra-compact Johansson-type X-ray fluorescence spectrometer with a Roland circle radius of 100 mm”, Advances in X-ray analysis, Vol. 35, 2004, p.201-208 S. Hayakawa, Y. Kagoshima, Y. Tsusaka, J. Matsui and T. Hirokawa, “High resolution X-ray fluorescence measurements using a flat analyzer and anX-ray CCD”, J. Trace and Microprobe Technique, 2001, 19 , p.615-621 C. Bonte, M. Harmand, F. Dorchiesa, S. Magnan, V. Pitre, and J.-C.Kieffer, P. Audebert and J.-P. Geindre, “High dynamic range streak camera forsubpicosecond time-resolved x -ray spectrometry ”, Rev. Sci. Instrum., 2007, 78, p.043503 K. Nakajima, K. Fujiwara, W. Pan and H. Okuda, “Shapedsilicon-crystal wafers obtained by plastic deformation and their application tosilicon-crystal lenses”, Nature Materials, 2005, 4, p.47-50

  However, the non-scanning wavelength dispersion type X-ray analyzer using the cylindrical curvature distribution crystal lens described in Patent Document 1 still requires a long detector when detecting a plurality of elements at the same time. That is, the distance L from the sample to the focal point when a cylindrical crystal is used is given by the following formula (1).

Here, r _s is the radius of curvature of the crystal, d is the lattice spacing of the crystal, λ is the X-ray wavelength, and n is an integer of 1 or more.

For example, if a cylindrical crystal of r _s = 50 mm and Ge (220) plane is used, a length of 7 cm or more is required if simultaneously analyzing elements from Ni to Ga (Ni, Cu, Zn, Ga). A detector is required. If the number of elements is further increased, a longer length is required. At present, the maximum size of the direct imaging system (type that does not convert with a scintillator) is 2cm x 2cm, and even if it is directly applied to a non-scanning wavelength dispersion X-ray analyzer, it is efficient. There was a problem that it was difficult to measure. Further, since it is necessary to arrange the surface of the detector so as to include the central axis of the cylinder, as shown in FIG. 14, the incident angle becomes a considerably low angle of about 10-20 ° with respect to the detection surface, and the spot is formed. There were also problems of easy bleeding and low spectral energy resolution.

  Further, even those using the conical crystals described in Non-Patent Document 5 cannot receive X-rays with a large solid angle, and there is a problem that it is difficult to measure efficiently.

  The present invention has been made by paying attention to such a problem, and a spectroscopic crystal and a wavelength dispersive X-ray analyzer that can detect more elements simultaneously and efficiently and can improve the energy resolution of the spectrum. And an element distribution measurement method.

  In order to achieve the above object, a spectroscopic crystal according to the present invention is a spectroscopic crystal that is used by being disposed between a sample and a detector in wavelength dispersion X-ray analysis, and is along a predetermined reference line. An inner surface having a shape formed by connecting arcs perpendicular to a reference plane including the reference straight line, the curvature of the arc changing along the reference straight line, and an arc-containing plane including the arc An angle formed with the reference straight line is configured to change.

  Particularly, in the spectroscopic crystal according to the present invention, the inner surface has a radius of curvature of the arc that decreases from the sample toward the detector along the reference straight line, and the arc and the reference plane intersect. It is preferable that the angle formed between the arc intersection, the line segment connecting the reference straight line and the reference intersection where the arc-containing plane intersects, and the reference straight line on the sample side from the reference intersection is reduced. .

  Further, the wavelength dispersion type X-ray analyzer according to the present invention is arranged so that the reference straight line coincides with an axis connecting the sample and the detector, or parallel to the axis in the reference plane. A spectral crystal according to the present invention, a light source for irradiating the sample with X-rays or electron beams, and a linear or planar detection unit for detecting X-rays, the detection unit being configured with respect to the axis And the detector arranged to be vertical.

Hereinafter, the principle of the spectral crystal according to the present invention and the wavelength dispersion X-ray analyzer according to the present invention using the spectral crystal will be described.
As shown in FIG. 1, when a conical crystals, the axis connecting the X-ray generating point (sample) p _s and the focal point p _f, the center axis of the cone-like crystal (vertex and the base of the cone And the same axis as the x-axis in FIG. 1). The wavelength of the X-ray that causes diffraction by this crystal is determined by the following Bragg equation.

Here, d is an interval between lattice planes, and θ is an angle formed by the lattice plane and incident X-rays, and is usually called a Bragg angle. Λ is the wavelength of X-rays, and n is a positive integer. Since all the X-rays irradiated from the X-ray generation point p _s to the arc (conical cut circle) portion of the conical crystal indicated by l have the same viewing angle θ with respect to the lattice plane, the equation (2) From this, it is understood that X-rays having the same wavelength λ are diffracted. The diffracted X-ray travels again toward the rotation center axis. Let L ₁ be the distance from the center point p ₁ to p _{s of} this conical cut circle. In addition, the distance from the _{p l} to the focal point _{p f} and _{L 2.} At this time, the values of L ₁ and L ₂ can be calculated by the following equations.

Here, r is the radius of curvature of the crystal, and α is the angle between the crystal surface and the rotation center axis. From equation (2), it can be seen that θ is a function of λ.

FIG. 2 shows an example in which a portion of the conical crystal shown in FIG. 1 which has been cut into appropriate thicknesses is arranged as an example (indicated by a, b, c and d in FIG. 2). Here, a part of each conical crystal is arranged at a different inclination and a different location of the rotation center axis. β _a , β _b , and β _d are inclinations from the normal of the detection surface or detection axis (detection unit) of the detector indicated by F. Note that the conical crystal c has a rotation center axis parallel to the detection surface of the detector or the normal of the detection axis (β _c = 0 °), and is not shown in FIG. In addition, α of the conical crystals a, b, c, and d are α _a , α _b , α _c , and α _d , respectively. X-rays (fluorescence X-rays and characteristic X-rays) of wavelengths λ _a , λ _b , λ _c , and λ _d at the arcs l _a , l _b , l _c , and l _d of the conical crystals a, b, c, and d, respectively. Shall be reflected. _Let radii of curvature at l _a , l _b , l _c , and l _d be r _a , r _b , r _c , and r _d , respectively. Here, the relationship between λ _a , λ _b , λ _c , and λ _d is λ _a <λ _b <λ _c <λ _d .

As shown in FIG. 2, the distances p _s -p _fa , p _s -p _fb , p _s -p _fc , and p _s -p _fd are D / cos (β _a ) and D / cos (β _b ), respectively. , D, D / cos (β _d ). Here, D is the distance from p _s to the detector F. However, when β is a low angle of 5 ° or less, the distances p _s −p _fa , p _s −p _fb , p _s −p _fc , and p _s −p _fd can all be approximated to D. Here, from the equations (2), (3), and (4), it can be seen that when λ is increased while the distance D to the focal point is kept constant, it is basically necessary to increase r. . Therefore, in order to satisfy λ _a <λ _b <λ _c <λ _d , it is necessary to satisfy r _a <r _b <r _c <r _d . Further, if the crystal position is a midpoint between p _s (sample) and F (detector), α = 0 °, and it is necessary to increase α as the midpoint approaches the detector. Also, α needs to be reduced as it approaches p _s . Therefore, a relationship of α _a <α _b <α _c <α _d is required for α.

As a result, as shown in FIG. 2, the arrangement of a part of the four conical crystals a, b, c and d makes the detection surface / detection axis (vertical) relatively perpendicular to the X-ray traveling direction. X-rays having four different wavelengths λ _a , λ _b , λ _c , and λ _d can be imaged on the detector F in which the detection unit) is disposed. Also, by changing the parameters α, β and r along with the change in position on the crystal in the direction from p _s to F, X-rays having different wavelengths (fluorescent X-rays and characteristic X-rays) can be converted into X-rays. It is possible to form an image relatively perpendicular to the traveling direction.

In FIG. 2, a part of four conical crystals is used, but a part of a larger number of conical crystals are arranged in a piecewise manner, the width of the crystals is reduced, and complemented with a spline curve. A smooth curved surface shape can be assumed. In the spectral crystal and wavelength dispersive X-ray analyzer according to the present invention, for example, the rotation center axis of the conical crystal c shown in FIG. 2 is a reference straight line (Lb in FIG. 2A), and FIG. ) And a plane perpendicular to the paper surface (a surface corresponding to the paper surface of FIG. 2A) including an axis connecting p _s (sample) and p _f (detector) is a reference plane. Part of the shaped crystal corresponds to the arc, and the smooth curved surface corresponds to the inner surface.

Therefore, the spectral crystal and the wavelength dispersion type X-ray analyzer according to the present invention are non-scanning type, and can detect more elements simultaneously and efficiently than the scanning type, and the measurement time. Can be greatly shortened. Further, by arranging the detector so that the detection unit (detection surface or detection axis) is perpendicular to the axis connecting the sample (p _s ) and the detector (F), the incident angle to the detection unit is reduced. Since it is close to vertical, the energy resolution of the spectrum can be increased. Further, the radius of curvature of the arc decreases from the sample ( _ps ) toward the detector (F), and an arc intersection where the arc and the reference plane intersect (Parc in the case of the cone d in FIG. 2A). And a line segment connecting the reference straight line Lb and the reference intersection point where the arc-containing plane intersects (Pb in the case of the cone d in FIG. 2A) and the reference straight line Lb on the sample side from the reference intersection point (Pb) These effects are particularly high when the angle formed is small.

  Further, as shown in FIG. 3A, the portion corresponding to the backbone of the spectroscopic crystal, that is, the portion AB in which the arc intersections (Parc) where the arc and the reference plane intersect with each other is a straight line. As shown in FIG. 3B, the maximum focal distance can be shortened by bending the portion AB corresponding to the spine. For this reason, in the case of FIG.3 (b), more elements can be detected simultaneously and efficiency is good. Further, the detector can be made smaller or a commercially available one can be used, so that the material cost of the detector can be reduced and the apparatus can be downsized.

  In the spectral crystal according to the present invention, in order to perform X-ray analysis with high accuracy, it is preferable that the crystal orientation is controlled with an accuracy of at least 0.1 degrees or less perpendicular to the inner surface. In addition, the detector includes, for example, a two-dimensional planar detection unit, an X-ray CCD (charge-coupled device), an imaging plate, and the like, and a one-dimensional linear detection unit. It is preferably composed of PSPC (position sensitive proportional counter), PAD (pixel array detector) and the like.

  The spectral crystal according to the present invention is preferably made of any one of Si, Ge, and SiGe. In this case, a spectral crystal suitable for X-ray analysis can be obtained. The spectral crystal according to the present invention is preferably formed by plastic working a single crystal plate at a temperature near its melting point. In this case, processing accuracy is good, and X-ray analysis can be performed with high accuracy. Also, the crystal orientation can be easily controlled with an accuracy of at least 0.1 degrees or less perpendicular to the inner surface.

In the spectral crystal according to the present invention, a multilayer film having a predetermined film interval may be provided on the surface of the inner surface. In this case, X-ray analysis can be performed even in a soft X-ray region having relatively low energy. The multilayer film is composed of, for example, a combination of a material having a relatively high density such as (W / C) _n and (Mo / Si) _n and a material having a small density.

  In the wavelength dispersive X-ray analyzer according to the present invention, the light source preferably has a side length of 300 μm or less in a direction parallel to the axis of the X-ray or electron beam to be irradiated. In this case, energy resolution can be increased. For example, when 8 keV X-rays are used, a resolution of 5 eV can be achieved with the detector.

  In the wavelength dispersive X-ray analyzer according to the present invention, the spectroscopic crystal is composed of a plurality of pieces, each of which has a different shape on the inner surface, and X-rays generated by different element regions that are separated from each other are detected by the detector. It may be arranged as follows. In this case, all X-rays (fluorescent X-rays and characteristic X-rays) cannot be measured over a wide elemental area with a single spectroscopic crystal due to restrictions on the area of the spectroscopic crystal and the size of the detector. Even if it exists, it can measure over a wide elemental area | region at once with several spectral crystals.

  In the element distribution measurement method according to the present invention, the light source of the wavelength dispersive X-ray analyzer according to the present invention emits X-rays or electron beams so as to scan the surface of the sample, and each irradiation position of the sample The X-ray corresponding to is detected by the detector, and element distribution information of the sample is obtained based on the detection result and the irradiation position of the sample corresponding to the detection result.

  According to the element distribution measuring method according to the present invention, so-called element mapping can be easily performed. Since the element distribution measuring method according to the present invention uses the wavelength dispersive X-ray analyzer according to the present invention, it is possible to measure a plurality of elements at the same time, compared to the case of using a scanning X-ray analyzer, Measurement time can be greatly shortened. In order to improve measurement accuracy, it is preferable that the X-ray or electron beam emitted from the light source is narrowed to a beam diameter of several microns or less.

  According to the present invention, it is possible to provide a spectroscopic crystal, a wavelength dispersive X-ray analyzer, and an element distribution measuring method that can detect more elements simultaneously and efficiently and can enhance the energy resolution of the spectrum. .

It is the (a) side view and (b) front view which show the principle of the spectroscopy and condensing in the conical crystal regarding the spectral crystal concerning this invention. (A) Side view, (b) showing the principle when a portion of four conical crystals having different parameters shown in FIG. 1 are arranged and condensed on one surface, concerning the spectral crystal according to the present invention. It is a top view. It is a side view in the case where (a) the part corresponding to the spine is a straight line, and (b) the part corresponding to the spine is curved, illustrating the principle of spectral and condensing of the spectral crystal according to the present invention. 1 is a side view showing a spectral crystal and a wavelength dispersive X-ray analyzer according to an embodiment of the present invention. It is a side view of the range from a sample to a detector of the spectral crystal and wavelength dispersion type X-ray analyzer shown in FIG. FIG. 5 is a perspective view of a range from a sample to a detector of the spectral crystal and wavelength dispersive X-ray analyzer shown in FIG. 4. FIG. 5 is a perspective view showing an arrangement example of the spectral crystal and the wavelength dispersive X-ray analyzer shown in FIG. 4 when there are a plurality of spectral crystals. It is a side view explaining the design principle of the shape of a spectral crystal of the spectral crystal and wavelength dispersion type | mold X-ray analyzer shown in FIG. FIG. 8 shows (a) a fluorescent X-ray condensing pattern of a sample containing five elements, and (b) an X-ray of the condensing pattern of the spectroscopic crystal and wavelength dispersive X-ray analyzer shown in FIG. The graph which shows intensity distribution, (c) It is a fluorescent X-ray condensing pattern at the time of changing a sample into a pure element. It is a side view which shows the conventional general wavelength dispersion type | mold fluorescence X-ray-analysis apparatus. It is a side view which shows the wavelength dispersion type characteristic X-ray analyzer by the conventional concentration system. It is a perspective view which shows the conventional non-scanning wavelength dispersion type | mold X-ray-analysis apparatus using a flat plate spectral crystal. It is a perspective view which shows the conventional non-scanning wavelength dispersion type | mold X-ray-analysis apparatus using a conical crystal. It is a side view which shows the conventional non-scanning wavelength dispersion type | mold X-ray-analysis apparatus using a cylindrical crystal.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
4 to 9 show a spectroscopic crystal and a wavelength dispersive X-ray analyzer according to an embodiment of the present invention.
As shown in FIGS. 4 to 6, the wavelength dispersion type X-ray analyzer 10 is a non-scanning type, and includes a light source 11, an XZ stage 12, a spectral crystal 13, and a detector 14.

As shown in FIG. 4, the light source 11 is composed of a rotating counter-cathode type X-ray generator using a Mo target, and can irradiate X-rays. The light source 11 is configured to limit the beam size to 150 × 150 μm ² by a slit 15 disposed in front.

  The XZ stage 12 is configured to install the sample 1 to be analyzed. The XZ stage 12 emits fluorescent X-rays or characteristic X-rays by irradiating the installed sample 1 with X-rays from the light source 11 and exciting them. The XZ stage 12 can adjust the emission direction of fluorescent X-rays from the sample 1 by adjusting the angle with respect to the light source 11.

  As shown in FIGS. 4 to 6, the spectroscopic crystal 13 has a shape based on the principle described with reference to FIGS. The spectral crystal 13 is made of any one of Si, Ge, and SiGe, and is formed by plastic working by pressing the single crystal plate at a temperature near its melting point. Thereby, the orientation of the crystal of the spectroscopic crystal 13 is controlled with an accuracy of at least 0.1 degrees or less perpendicular to the inner surface. The spectral crystal 13 is arranged such that the reference straight line Lb coincides with the axis connecting the sample 1 and the detector 14. The spectroscopic crystal 13 is installed on a five-axis stage, and the angle with respect to the sample 1 and the detector 14 can be finely adjusted.

  The detector 14 is composed of an X-ray CCD, and has a planar detector 14a that detects X-rays. The detector 14 is arranged such that the detection unit 14 a is perpendicular to the axis connecting the sample 1 and the detector 14.

Next, the operation will be described.
The wavelength dispersive X-ray analyzer 10 causes the spectral crystal 13 to emit fluorescent X-rays or characteristic X-rays that are relatively perpendicular to the radial direction centering on the X-ray source of the sample 1. It is possible to focus in the direction by arranging in different positions depending on the wavelength. They are distributed on a straight line, and the intensity distribution corresponds to the spectrum of fluorescent X-rays or characteristic X-rays. The plurality of spectra can be detected simultaneously by the detector 14.

  When the wavelength dispersive X-ray analyzer 10 uses, for example, a Ge (110) spectral crystal 13 having a curvature radius of 50 to 30 mm, fluorescent X-rays of 4 to 5 elements in a range of 2 to 3 cm. Can be focused. For this reason, even if a commercially available X-ray CCD is used as the detector 14, it can respond sufficiently. As a specific example, as shown in FIG. 3A, when the portion AB corresponding to the spine of the spectral crystal 13 is linear, the Cr included in the region having a Bragg angle of 10.2 to 32.7 °. Table 1 shows parameters such as the radius of curvature and the axis tilt of the spectroscopic crystal 13 using the Ge (110) substrate for condensing the K-line of Mo. Table 1 shows the energy range (Bragg angle) of the fluorescent and characteristic X-rays that can be covered and the elements that can be analyzed when three types of spectral crystals 13 having a radius of curvature of 60 to 50, 50 to 30, and 30 to 20 mm are used. Range.

  In addition, the graphite mold for shape crystal processing for manufacturing the spectral crystal 13 is prepared by drawing with a three-dimensional CAD based on the parameters shown in Table 1 and the like and using a five-axis processing machine. Can do.

  Thus, the spectroscopic crystal 13 and the wavelength dispersive X-ray analyzer 10 are non-scanning, and can detect more elements simultaneously and efficiently than the scanning type, greatly increasing the measurement time. Can be shortened. Thereby, damage to the sample 1 can be prevented. In addition, since the detection unit 14a is arranged so as to be perpendicular to the axis connecting the sample 1 and the detector 14, the incident angle to the detection unit 14a becomes nearly vertical, and the energy resolution of the spectrum can be improved. it can. Further, the detector can be made smaller or a commercially available one can be used, so that the material cost of the detector can be reduced and the apparatus can be downsized. In a specific example shown in Table 1, the focal length can be shortened to about 20 mm, and the apparatus can be made very compact.

The spectral crystal 13 may be provided with a multilayer film having a predetermined film interval on the inner surface. The multilayer film is composed of, for example, a combination of a material having a relatively high density such as (W / C) _n and (Mo / Si) _n and a material having a small density. Table 2 shows the energy range that can be covered when an artificial multilayer film having a surface spacing of 5 nm is prepared on the inner surface of the spectral crystal 13 and used for spectroscopy. As shown in Table 2, by using an artificial multilayer film, X-ray analysis can be performed even in a soft X-ray region having relatively low energy.

  Further, as shown in FIG. 7, the spectroscopic crystal 13 includes a plurality of crystals, each of which has a different shape on the inner side surface, and is arranged so that X-rays generated by different element regions that are spectrally separated can be detected by the detector 14. Also good. In this case, all the X-ray (fluorescent X-ray and characteristic X-ray) spectra are measured with a single spectral crystal 13 over a wide elemental area at a time due to limitations on the area of the spectral crystal 13 and the size of the detector 14. Even when it is not possible, measurement can be performed over a wide elemental region at once by the plurality of spectral crystals 13.

Next, a measurement example using the spectral crystal 13 and the wavelength dispersive X-ray analyzer 10 will be described.
Here, a Ge (110) single crystal is used as the spectroscopic crystal 13, and a crystal corresponding to a Bragg angle of 18 to 25 ° is produced so that elements from Ni to Ge can be condensed using Ge (220) diffraction. did.

  The curved surface required for the spectral crystal 13 was designed using a three-dimensional CAD (computer aided design). As shown in FIG. 8, it is assumed that the prototype spectral crystal 13 has a spine parallel to the normal direction of the detector 14 and the distance between the spine and the X-ray source (sample 1) is 50 mm. And produced. At this time, the X-ray with a Bragg angle of 25.0 ° was received at the end of the spectral crystal 13 on the radiation source side with a radius of curvature of 50 mm and an axial inclination of 0.0 °. At this time, the distance of “sample 1 (X-ray source)” − “end of the spectral crystal 13 on the source side” − “detector 14” is determined to be 107.2 mm. Fluorescent X-rays incident on the backbone of the spectral crystal 13 at a Bragg angle unique to each element are reflected at an angle equal to that and reach the detector 14. In order to collect light at this arrival point, the line connecting the arrival point and the X-ray source may be used as the central axis, and a perpendicular line drawn down this axis is necessary for condensing each fluorescent X-ray. The radius of curvature. Since the positional relationship among the X-ray source, the spectroscopic crystal 13 and the detector 14 has already been determined, given the conditions that the Bragg angle specific to each element and the detector side end of the crystal are incident at 18.0 °, The inclination of the axis of intersection between the axis connecting the sample 1 and the detector 14 in the radius of curvature and the circle of curvature (a circle including an arc) and the intersecting axis are naturally determined. Table 3 shows main parameters that define the shape of the prototyped spectral crystal 13.

  After drawing the curvature circles corresponding to each end of the spectroscopic crystal 13 and each element on the three-dimensional CAD, the curved surface shape is determined by automatically generating curved surfaces so as to smoothly connect these circles. did. A high-temperature pressurizing die having this curved surface was designed on the same CAD, and the information was sent to a 5-axis machine connected to the CAD system to process the graphite into the required die shape.

  A Ge (110) single crystal wafer is sandwiched between molds, heated to a temperature close to the melting point (938 ° C.) in an inert gas atmosphere, and then pressed to maintain a desired flat single crystal wafer while maintaining its crystallinity. Processing into the shape of the spectral crystal 13. In this example, a 53 × 49 × 0.5 (thickness) mm Ge (110) single crystal wafer was held at 900 ° C. in an Ar atmosphere, and then a 50 kgf load was applied to the mold. High-temperature pressure processing was performed.

For sample 1, an alloy containing five elements (Ni, Cu, Zn, Ga, Ge) was used, and X-rays were irradiated to the alloy to generate fluorescent X-rays. The light source 11 (X-ray source) for exciting the alloy is a rotating anti-cathode type X-ray generator using a Mo target, and the X-ray beam size is limited to 150 × 150 μm ² by the slit 15.

FIG. 9A shows a fluorescent X-ray condensing pattern of five elements contained in the alloy measured by an X-ray CCD. As shown in FIG. 9, the measured pattern, a fluorescent X-ray from the plurality of elements are condensed separately, K [alpha line of each element are clearly separated in K [alpha ₁ and K [alpha _2. FIG. 9B shows a result obtained by averaging (integrating) these patterns in the direction of the arrow in FIG. In FIG. 9B, the horizontal axis represents the number of measured CCD channels, and the vertical axis represents intensity (arbitrary unit). Further, FIG. 9C shows a fluorescent X-ray condensing pattern when the sample 1 is changed to a pure element (Ni 99 +%, Cu 99.96%, Zn 99.5%, Ge single crystal). Based on FIG. 9C, the peak of FIG. 9B is identified. From the half width of the Cu Kα ₁ peak, the energy resolution can be calculated to be about 13 eV.

  As described above, according to the spectroscopic crystal 13 and the wavelength dispersive X-ray analyzer 10, the light receiving solid angle of fluorescent X-rays and characteristic X-rays is large, and high-resolution spectra of a plurality of elements can be detected simultaneously. Measurement time can be dramatically shortened. For example, the measurement time can be shortened by about 1 to 2 digits as compared with a conventional scanning X-ray analyzer. For this reason, the chromatic dispersion method can be applied even to a cold type FE-SEM with low output but high resolution, which has been difficult in the past.

  As a method for measuring the element distribution according to the embodiment of the present invention, the surface of the sample 1 is scanned with X-rays or electron beams from the light source 11 using the spectral crystal 13 and the wavelength dispersive X-ray analyzer 10. The X-ray corresponding to each irradiation position of the sample 1 is detected by the detector 14, and the element distribution information of the sample 1 may be obtained based on the detection result and the irradiation position of the corresponding sample 1. .

  According to the element distribution measuring method of the embodiment of the present invention, so-called element mapping can be easily performed. In the case of using a conventional scanning type wavelength dispersion type measuring apparatus, basically only one element can be measured at a time. Therefore, it takes a long measuring time to measure several elements simultaneously. On the other hand, in the element distribution measurement method according to the embodiment of the present invention, since the wavelength dispersion type X-ray analyzer 10 is used, a plurality of elements can be measured at the same time, and the measurement time can be greatly shortened. . In order to increase the measurement accuracy, the X-ray or electron beam emitted from the light source 11 is preferably narrowed to a beam diameter of several microns or less.

  Further, according to the spectral crystal 13 and the wavelength dispersive X-ray analyzer 10, reverse X-ray photoelectron holography, which is a three-dimensional atomic imaging technique around a specific element, can be performed with high accuracy. Inverse X-ray photoelectron holography is a technique for measuring the intensity of characteristic X-rays as a function of sample orientation, and bremsstrahlung white X-rays are also detected simultaneously for electron beam excitation. Since this bremsstrahlung X-ray becomes a spectrum background, holographic measurement becomes difficult with a semiconductor detector having an energy resolution of about 150 eV, particularly when measuring trace elements of 0.1% or less. In the conventional wavelength dispersion type X-ray analyzer, since the solid angle of receiving characteristic X-rays is small and sufficient intensity cannot be obtained, holographic measurement is difficult. On the other hand, since the spectral crystal 13 and the wavelength dispersive X-ray analyzer 10 have high resolution, the lower detection limit of such trace elements can be improved, and high-precision holographic measurement can be performed.

  Further, according to the spectroscopic crystal 13 and the wavelength dispersive X-ray analyzer 10, by using the detector 14 capable of time-division measurement, the change in the X-ray spectrum of the sample during the reaction is measured and analyzed in real time. You can also.

DESCRIPTION OF SYMBOLS 1 Sample 10 Wavelength dispersive X-ray analyzer 11 Light source 12 XZ stage 13 Spectroscopic crystal 14 Detector 14a Detector 15 Slit

Claims (9)

A spectroscopic crystal that is used between a sample and a detector in wavelength dispersive X-ray analysis,
An inner surface having a shape formed by connecting arcs perpendicular to a reference plane including the reference line along a predetermined reference line, and the curvature of the arc changes along the reference line; An angle formed by an arc-containing plane including an arc and the reference straight line is configured to change.
Spectral crystal characterized.   The inner surface has an arc intersection where the radius of curvature of the arc decreases from the sample toward the detector along the reference straight line, and an arc intersection where the arc and the reference plane intersect, and the reference straight line and the arc. 2. The spectroscopic crystal according to claim 1, wherein an angle formed by a line segment connecting a reference intersection where the contained plane intersects with the reference straight line on the sample side from the reference intersection is reduced. .   3. The spectral crystal according to claim 1, wherein the spectroscopic crystal is made of any one of Si, Ge, and SiGe.   4. The spectroscopic crystal according to claim 1, 2 or 3, wherein the single crystal plate is formed by plastic working by pressing at a temperature near its melting point.   5. The spectroscopic crystal according to claim 1, wherein a multilayer film having a predetermined film interval is provided on a surface of the inner surface. 6. The spectroscopic method according to claim 1, wherein the reference line is arranged so as to coincide with an axis connecting the sample and the detector, or to be parallel to the axis in the reference plane. Crystals,
A light source that emits X-rays or electron beams toward the sample;
The detector having a linear or planar detection unit for detecting X-rays, wherein the detection unit is arranged to be perpendicular to the axis;
A wavelength dispersive X-ray analyzer characterized by comprising:   The wavelength dispersion type X-ray analyzer according to claim 6, wherein the light source has a side length of 300 μm or less in a direction parallel to the axis of the X-ray or electron beam to be irradiated.   The said spectroscopic crystal consists of two or more, respectively, The shape of the said inner surface differs, It arrange | positions so that the X-ray by the different element area | region which each may disperse | distributes may be detected with the said detector. 6. A wavelength dispersive X-ray analyzer according to 6 or 7. An X-ray or an electron beam is irradiated from the light source of the wavelength dispersive X-ray analyzer according to claim 6, 7 or 8 so as to scan the surface of the sample, and the X-ray corresponding to each irradiation position of the sample Is detected by the detector, and element distribution information of the sample is obtained based on the detection result and the corresponding irradiation position of the sample.