JP3339267B2 - X-ray analysis method and X-ray analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray analysis method for irradiating a sample with primary X-rays, measuring the energy of fluorescent X-rays emitted from the sample, and analyzing the components of the sample. It relates to an analyzer.

[0002]

2. Description of the Related Art Conventionally, as a method for analyzing a component on a sample surface, a sample is irradiated with a narrowly focused radiation beam such as an electron beam or an X-ray while two-dimensionally scanning the same, and fluorescent X-rays generated from the sample are subjected to an energy dispersive method. (For example, Japanese Patent Application Laid-Open No. 4-175648, "X-ray microanalyzer" (Nikkan Kogyo Shimbun)). For example, in an X-ray microanalyzer (EPMA), a primary beam, which is a narrowed electron beam, is two-dimensionally scanned on a sample surface, and the wavelength dispersion of fluorescent X-rays (characteristic X-rays) emitted from the sample is analyzed by a spectral crystal. (LiF, NaCl, SiO ₂ , penta-erythritol, ethylenediamine tartrate, etc.), and X-rays of a specific wavelength (characteristic X-rays of the element to be measured) among the wavelength-dispersed X-rays are measured by a proportional counter. Analysis is performed on the elements constituting the sample by detection using a scintillation counter, a detector including a single detection window made of a semiconductor or the like.

[0003]

However, these analyzers require a long time of several tens of minutes to several hours for one data measurement / acquisition in order to scan the sample by narrowing the radiation beam. In addition, since the electron beam or the X-ray enters the inside of the sample, the spatial resolution of the measured element distribution is several tens μm.
m to several hundred μm, and no further improvement can be expected. Furthermore, since the sample is exposed to the narrowed radiation for a long time, there is a problem that the sample is easily damaged particularly with a polymer material or the like, and it is not possible to observe a temporal change in the same sample.
Some of the samples to be observed are moving by external force and others are changed by reaction.However, the conventional beam scanning analysis method requires a long time and may damage the sample. Observation of such a sample was not possible.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to perform elemental analysis of a sample in a short time without beam scanning of radiation as in the prior art, and It is an object of the present invention to provide an X-ray analysis method and an X-ray analysis apparatus capable of reducing damage due to irradiation and further capable of measuring a sample over time and measuring dynamics.

[0005]

(First Invention) The X-ray analysis method according to the first invention provides a laser beam generated by a laser generator.
Laser light is focused using a lens, and the focused laser
Laser plasm by irradiating the target with light in a vacuum chamber
Generate soft X-rays and apply the laser plasma soft X-rays to the sample
Irradiate two-dimensionally to have a predetermined area and emit from the sample
Detects soft X-rays generated by X-ray shielding means having holes
The two-dimensional image is formed so as to have a predetermined area on the
Based on the energy of the fluorescent X-rays detected by
It is characterized by two-dimensional analysis of components contained in the ingredients
And

[0006] The irradiation of the laser plasma soft X-rays causes the electrical energy of the sample to be in an excited state. The excited electrons emit fluorescent X-rays (characteristic X-rays) when returning to the ground state of the K, L, M, N, and O shells. This fluorescent X
Since the energy of the line differs depending on the element, the element can be analyzed by measuring the energy. X of the present invention
In the X-ray analysis method, since the X-ray shielding means having a hole is provided between the sample and the detector, the fluorescent X-rays on the sample surface are imaged on the detector surface by the X-ray shielding means having the hole. (A pinhole camera using so-called X-rays as a light source). Since there is no substance having a role of a lens in visible light with respect to X-rays, at present, only a reflection mirror, a Fresnel zone plate, and the pinhole camera of the present invention exist to form an image using X-rays. Reflection mirrors are not suitable as imaging means for quantitative evaluation because the reflectance greatly changes depending on the wavelength of X-rays and the angle of incidence on the mirror. On the other hand, the so-called pinhole camera using X-rays as a light source according to the present invention is suitable for imaging of fluorescent X-rays since the wavelength and the imaging position are arbitrary.

(Second Invention) The X-ray analysis method of the second invention is characterized in that, in the first invention, the detector is a two-dimensional energy dispersive detector.

[0008] Since the detector is a two-dimensional energy dispersive detector, a signal based on the energy of the fluorescent X-rays passing through the hole can be output, and the two-dimensional elemental analysis of the sample can be performed by using a conventional beam detector. This is possible without scanning.

(Third Invention) In the X-ray analysis method according to the third invention, in the first invention, the hole diameter of the X-ray shielding means is 0.1.
１００100 μm.

When the hole diameter of the X-ray shielding means is less than 0.1 μm, the amount of light to the detector becomes insufficient. In addition, the detector cell size (10 μm or more) and magnification (100 times or less)
It is not necessary that the thickness be 0.1 μm or less. Also, 100
If it exceeds μm, the spatial resolution is extremely reduced. The resolution Δ can be approximately expressed by equation (1) using the pinhole size a and the magnification m.

Δ ≒ a (1+ (1 / m)) (1)

From the equation (1), when the hole of the X-ray shield, that is, the pinhole diameter is 100 μm or more, the resolution Δ is 100 μm.
This is not preferred because of the above.

(Fourth Invention) In the X-ray analysis method according to the fourth invention, in the second invention, the two-dimensional energy dispersive detector comprises an aggregate of cells having a cross section of 1 to 100 μm. It is characterized by the following.

If the size of the cross section of the two-dimensional energy dispersive detector is less than 1 μm, the amount of fluorescent X-rays to be detected becomes insufficient, and it takes a long time to perform one analysis. On the other hand, when the thickness exceeds 100 μm, the spatial resolution is increased to 100 μm or more, which is not preferable.

In the X-ray analysis method of the present invention, the sample
The primary radiation to irradiate the laser plasma soft X-rays.

Since the primary radiation is a laser plasma soft X-ray, it is not affected by an electromagnetic field, temperature, environment, etc.
Measurements can be made in magnetic fields, electric fields, high and low temperatures, and in the atmosphere.

[0017]

[0018]

( Fifth Invention) The X-ray analyzer according to the fifth invention comprises a sample stage on which a sample is mounted, and a laser beam generator.
Laser generating device, and a lens for condensing the laser light
Laser beam from the focused laser beam.
And a target for generating soft X-rays.
Irradiate plasma soft X-ray two-dimensionally to have a predetermined area
Primary radiation irradiating means, and the laser plasma soft X-ray
X-ray fluorescence emitted from the sample by irradiation
A detector to be detected, and a detector installed between the sample and the detector.
A predetermined area of the fluorescent X-rays emitted from the sample is applied to the detector.
X-ray shielding hand with a two-dimensional imaging hole to hold
A step and at least the target, the detector and the hole
And a vacuum chamber for storing the X-ray shielding means.
And features.

According to the X-ray analyzer of the fifth aspect of the present invention, elemental analysis of a sample can be performed by the same operation as in the first aspect of the present invention.
That is, an image of fluorescent X-rays emitted from the sample by the irradiation of the laser plasma soft X-rays is formed on the detector by a hole provided between the sample and the detector. Can be subjected to elemental analysis.

In the X-ray analyzer of the present invention, the sample
The primary radiation to irradiate the laser plasma soft X-rays.

Since the primary radiation is a laser plasma soft X-ray, it is not affected by an electromagnetic field, temperature, environment, etc.
Measurements can be made in magnetic fields, electric fields, high and low temperatures, and in the atmosphere.

[0023]

[0024]

( Sixth Invention) The X-ray analyzer according to the sixth invention is characterized in that, in the fifth invention, the detector is a two-dimensional energy dispersive detector.

Since the detector is a two-dimensional energy dispersive detector, a signal based on the energy of the fluorescent X-rays passing through the hole can be output, and the two-dimensional elemental analysis of the sample can be performed by the beam as in the prior art. This is possible without scanning.

( Seventh invention) In the X-ray analyzer according to the seventh invention, in the fifth invention, the X-ray shielding means has a hole diameter of 0.1.
１００100 μm.

According to the same function as the third aspect of the present invention, the X-ray shield preferably has a hole diameter of 1 to 100 μm.

( Eighth Invention) In the X-ray analyzer according to the eighth invention, in the sixth invention, the two-dimensional energy dispersive detector comprises an aggregate of cells having a cross section of 1 to 100 μm. It is characterized by the following.

It is preferable that the two-dimensional energy dispersive detector be constituted by an aggregate of cells having a cross section of 1 to 100 μm by the same operation as the fourth invention.

[0031]

According to the X-ray analysis method and the X-ray analysis apparatus of the present invention, elemental analysis of a sample can be performed in a short time without scanning a beam of radiation, and damage due to irradiation can be reduced. In addition, the change over time of the sample can be measured.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Specific Examples of the Invention)

As the detector, a semiconductor detector, a proportional counter, a scintillation counter, or the like can be used in addition to a two-dimensional energy dispersive detector. When the detector is constituted by cells, the shape of the cells does not necessarily have to be circular, and may be, for example, polygonal.

The shield having holes is not particularly limited as long as it can shield fluorescent X-rays, such as metal, ceramics, and polymer. In addition, the shape is not particularly limited as long as it can shield laser plasma soft X-rays from other than holes, such as a plate shape or a block shape. Further, a filter that shields or transmits radiation having a specific energy may be provided in the hole. Further, the shape of the hole is not necessarily required to be circular, but may be polygonal.

As the sample stage, a structure having a structure on which a sample can be placed, a structure having a structure capable of being fixed and suspended, and the like can be used.

The present invention will be specifically described with reference to FIG.
FIG. 1 shows a case where a laser plasma X-ray generator is used as primary X-ray irradiating means. In the figure, 1 is a laser generator, 2 is a lens for condensing a laser, 3 is a target for generating laser plasma X-rays, 4 is a vacuum vessel, 5 is an X-ray shield having a hole, 6 Denotes a sample, and 7 denotes a two-dimensional energy dispersive X-ray detector. Laser light generated from the laser generator 1 is condensed by a lens 2 and irradiates a target 3, where X-rays are generated. The generated X-rays irradiate the sample 6 placed on a sample stage (not shown), where fluorescent X-rays based on the constituent elements of the sample are generated. The generated fluorescent X-ray passes through the hole of the X-ray shield 5 and forms an image on the energy dispersive X-ray detector 7. Since the X-ray detector 7 is of the energy dispersive type, an output proportional to the energy of the fluorescent X-ray is obtained here, and thus the elemental analysis of the sample becomes possible.

The angle θ of the X-ray shield 5 and the X-ray detector 7 with respect to the primary X-ray incident angle is preferably in the range of 10 to 80 degrees when the sample 6 is a thick film or a bulk material. In this case, observation from the back side becomes possible, so 1
It may be 00 to 260 degrees.

By changing the distance between the X-ray shield 5 and the sample 6, the magnification of the image formed on the X-ray detector 7 can be adjusted.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Double harmonics (2ω: E = 0.4 J, t = 8 ns, λ = 53) of laser light from a YAG laser device
2 nm) on a carbon target using a lens with a diameter of 7
Condensed irradiation was performed so as to be 0 μm or less, and laser plasma soft X-rays were generated from a carbon target. The soft X-ray spectrum from the carbon target generated in this manner contained high-intensity soft X-rays having a wavelength of 2.5 nm. The sample was irradiated with soft X-rays from the carbon target, and fluorescent X-rays derived from constituent elements were generated from the sample. The fluorescent X-rays formed on the surface of the sample are passed through a hole having a diameter of 1 μm,
An image was formed on the line detection surface. The soft X-ray detection surface is a detection surface in which semiconductor detectors having a cell size of 10 μm are arranged in 512 rows and columns, and the energy dispersion spectrum of soft X-rays incident on each cell can be measured. By observing the intensity distribution for a specific wavelength of the spectrum measured in each cell, the distribution state of the constituent elements can be determined.

FIG. 2 is an image obtained by fluorescent X-rays of bromine penetrating into the inside of vinyl chloride when vinyl chloride is reacted with bromine. In the image, a portion that looks whitish contains a large amount of bromine. Part. The concentration distribution of bromine can be determined from the density of this image.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a typical configuration of the present invention.

FIG. 2 is a particle structure of bromine in vinyl chloride based on a fluorescent X-ray image.

[Explanation of symbols]

 3 Primary radiation generating and irradiating means 6 Sample 5 X-ray shielding means having holes 7 Detector

Continuation of the front page (56) References JP-A-4-175646 (JP, A) JP-A-2-187689 (JP, A) JP-A-5-99863 (JP, A) JP-A-7-20070 (JP) , A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 23/223 JICST file (JOIS)

Claims (8)

(57) [Claims] 1. A laser generated by a laser generator
The light is condensed using a lens, and the condensed laser light is
Irradiate the target in a vacuum chamber to soften the laser plasma
Generate X-rays, The laser plasma soft X-ray has a predetermined area on the surface of the sample
Irradiation in two dimensions X-ray shielding hand having a hole for fluorescent X-rays generated from the sample
Two-dimensionally image the detector with a predetermined area by the steps
Let Based on the energy of the fluorescent X-rays detected by the detector.
To analyze the components contained in the sample two-dimensionally.
An X-ray analysis method characterized by the following. 2. The X-ray analysis method according to claim 1, wherein
An X-ray analysis method, wherein the detector is a two-dimensional energy dispersive detector. 3. The X-ray analysis method according to claim 1, wherein
An X-ray analysis method, wherein the hole diameter of the X-ray shielding means is 0.1 to 100 μm. 4. The X-ray analysis method according to claim 2,
The two-dimensional energy dispersive detector has a cross section of 1 to 100.
An X-ray analysis method comprising a collection of cells having a size of μm. 5. A sample stage for mounting a sample, a laser generator for generating a laser beam, and the laser
A lens for condensing light and the condensed laser light
A target for generating laser plasma soft X-rays.
A laser plasma soft X-ray is applied to the surface of the sample over a predetermined area.
Primary radiation irradiating means for two-dimensionally irradiating the sample with the laser plasma soft X-rays;
A detector for detecting the fluorescent X-rays two-dimensionally, and a detector provided between the sample and the detector and emitted from the sample.
Fluorescent X-rays in a two-dimensional manner so that the detector has a predetermined area.
X-ray shielding means having an aperture for imaging an image, and at least the target, the detector, and the aperture
A vacuum chamber for storing the X-ray shielding means.
X-ray analyzer to be featured. 6. The X-ray analyzer according to claim 5 , wherein
An X-ray analyzer, wherein the detector is a two-dimensional energy dispersive detector. 7. The X-ray analyzer according to claim 5 , wherein
An X-ray analyzer, wherein the hole diameter of the X-ray shielding means is 0.1 to 100 μm. 8. The X-ray analyzer according to claim 6 , wherein
The two-dimensional energy dispersive detector has a cross section of 1 to 100.
An X-ray analyzer comprising an aggregate of cells having a size of μm.