JP2000162392A - Filter for soft x rays and soft x-ray measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a filter for soft X rays with sufficient wavelength selectivity and a soft X-ray measuring device by overlapping two types of thin films, namely a metal thin film and a non-metal thin film with different soft X-ray transmission characteristics. SOLUTION: Hard X rays are eliminated by a metal thin film as soft X-ray constituent, and soft X rays that could not be eliminated by a metal thin film and exceed a specific wavelength region are eliminated by a non-metal thin film, thus obtaining soft X rays at a narrow wavelength region. Metal such as Be, Al, Sc, Ti, and V is used as the raw material of a metal thin film. A thin film made of a macromolecular material such as polypropylene, polyethylene, and polyvinylchloride and a thin film made of such inorganic material as silicon nitride Si3N4 and silicon Si are used as the non-metal thin film. When Al thin film is used as the metal thin film, its film thickness is set to 0.01-0.2 μm. When polypropylene P and P thin film are used as the non-metal thin film, its film thickness is set to 1-5 μm. In the case of a filter where both of them are overlapped, improved transmission property is achieved with a wavelength of 4-7 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft X-ray filter capable of transmitting only soft X-rays having a wavelength within a specific range and a soft X-ray filter for measuring only soft X-rays having a wavelength within a specific range. The present invention relates to a line measuring device. Here, soft X-ray is 0.2n
X-rays having a wavelength of about m to several tens nm.

[0002]

2. Description of the Related Art Analysis using soft X-rays is widely used in the fields of living organisms, electronics, and materials. Such an analysis
This is performed by irradiating the object to be analyzed with soft X-rays and detecting the X-rays emitted by a detector. During such an analysis,
Since X-rays emitted from the X-ray source may include wavelengths other than soft X-rays, those other than soft X-ray components are removed from the X-rays emitted from the X-ray source. There is a need. Therefore, in order to convert the X-rays emitted from the X-ray source into soft X-rays, a filter for soft X-rays made of a thin film of a metal such as Al has been used as shown in JP-A-5-297148. Such a soft X-ray filter reflects ultraviolet light and hard X-rays and has a high transmittance for soft X-rays. Therefore, X-rays emitted from the X-ray source can be converted into soft X-rays by passing through such a filter.

[0003]

However, the conventional soft X-ray filter has a problem in that the soft X-ray transmitted through the filter contains a wide range of wavelength components, and sufficient wavelength selectivity cannot be obtained. Was. Unless sufficient wavelength selectivity is obtained, high-precision analysis cannot be performed. For example,
When observing living organisms, the soft X-rays used for analysis have significantly different transmittances for hydrocarbons and water.
It is desirable to use soft X-rays with a wavelength in the 4 nm water window region. This is because it is difficult to determine whether the transmitted substance is water or hydrocarbon when the measurement is performed using a soft X-ray including a wavelength region having a large transmittance for both hydrocarbon and water, for example, 4 to 7 nm. become. Therefore, in order to perform high-precision analysis, it is necessary to perform measurement using soft X-rays containing many wavelength components of 2.2 to 4.4 nm. Further, it is desirable to use soft X-rays containing a large number of wavelength components of 4 to 7 nm for the analysis of the organic thin film. This is for the same reasons as described above,
This is because if a wavelength component of 7 nm or more is contained, no difference in transmittance between organic substances is produced, and analysis becomes difficult.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a soft X-ray filter and a soft X-ray measuring device having a sufficient wavelength selectivity. It is in.

[0005]

In order to solve the above-mentioned problems, a soft X-ray filter according to the present invention comprises a metallic thin film and a non-metallic thin film having soft X-ray transmission characteristics different from those of the metallic thin film. And at least two types of thin films are overlapped with each other.

Generally, a metallic thin film has the property of reflecting light (electromagnetic waves) in the visible light region and transmitting X-rays in the soft X-ray region. In the soft X-ray region, soft X-rays in a part of the wavelength region are hardly transmitted, and the other wavelength regions are transmitted. Soft X of metal thin film
FIG. 15 shows transmission characteristics near the linear wavelength range. FIG. 15 shows the X-ray wavelength on the horizontal axis and the transmittance on the vertical axis. The transmittance of the metal thin film has a minimum value at a point A (hereinafter, referred to as point A) where the transmittance is minimum, and transmits soft X-rays in a wavelength region C shorter than the point A and a wavelength region B longer than the point A. I do. In particular, in a wavelength region B having a longer wavelength than the point A, the transmittance is high in a relatively wide range.

Therefore, if the wavelength component of the transmitted soft X-ray is to be in a narrow range, it is necessary to remove the soft X-ray in the wavelength region B shown in FIG. For this reason, the inventor of the present invention has studied to narrow the range of soft X-rays transmitted by superimposing another filter on the metal thin film. However, when a metal thin film filter generally known as a soft X-ray filter is stacked,
If the metal is different, the specific numerical value of the point A is different, but since the transmission characteristics are similar, the soft X-rays in the wavelength region B described above cannot be effectively removed.

Accordingly, the present inventors have conducted intensive studies and found that a non-metal thin film filter has a characteristic that a soft X-ray transmission range is narrow in a wavelength region B longer than point A. Do you get it. The inventors of the present invention have made the present invention based on such findings. That is, as shown in FIG. 16, the transmission characteristic of the nonmetallic thin film has a point A ′ at which the transmittance is minimum, a wavelength region C ′ shorter than the point A ′, and a wavelength region longer than the point A ′. The point where soft X-rays are transmitted in the region B 'is the same as that of the metal thin film, but has a characteristic that the soft X-rays are transmitted only in a relatively narrow wavelength range in the wavelength region B' longer than the point A '. In particular, the transmittance in a region having a longer wavelength than the point D 'shown in FIG. 16 was almost zero. Therefore, soft X-rays in the wavelength region above the point D 'can be removed by the non-metallic thin film filter.

Therefore, according to the soft X-ray filter of the present invention, at least two types of thin films of a metallic thin film and a non-metallic thin film having different soft X-ray transmission characteristics from the metallic thin film are used. Since they are superposed, the hard X-rays are removed by a metallic thin film to obtain a soft X-ray component, and the soft X-rays that could not be removed by the metallic thin film are further removed by the non-metallic thin film at the point D ′ described above. Soft X-rays in the above wavelength region are removed. Therefore, according to the soft X-ray filter of the present invention, soft X-rays in a narrow wavelength range can be obtained.

The soft X-ray filter of the present invention may be formed by depositing a metal thin film element on a nonmetallic thin film,
A non-metallic thin film and a metal thin film may be separately formed and then superposed. Further, the non-metallic thin film and the metal thin film do not necessarily need to be in contact with each other, and may be arranged separately. Further, it is not necessary to necessarily have a two-layer structure of a metal thin film and a non-metallic thin film, and a laminate of a metal thin film and a non-metal thin film in two or more layers may be used.
u, Au, Ni, Mo, Pt, Ag, W, etc.). In short, it is only necessary that X-rays pass through at least two kinds of thin films of Al and a nonmetallic thin film. Be, Al, Sc, T
i, V, Cr, Mn, Fe, Co, Ni, Cu, Zn,
Metals such as Mo, Ag, W, Pt, and Au can be used. Examples of the nonmetallic thin film include a thin film made of a polymer material such as polypropylene, polyethylene, and polyvinyl chloride, silicon nitride (Si ₃ N ₄ ), silicon (Si), silicon carbide (SiC), and aluminum oxide (Al ₂ ). A thin film made of an inorganic material such as O ₃ ) or boron nitride (BN) can be used.

It is preferable to use an Al thin film as the metal thin film. This is because Al is often used as a metallic filter for soft X-rays and can be obtained at low cost.

When an Al thin film is used as a metal thin film,
It is preferable that the film thickness is 0.01 to 0.2 μm. When the film thickness is less than 0.01 μm, the amount of soft X-rays absorbed is small, and soft X-rays in the wavelength region to be absorbed are transmitted.
Further, when the film thickness is 0.2 μm or more, the amount of soft X-rays absorbed increases, and soft X-rays having a wavelength to be transmitted are not transmitted.

When a polymer thin film is used as the nonmetallic thin film, it is preferable to use a polypropylene thin film. The soft X-ray transmission characteristics of the polypropylene thin film are in the range of 2 to 7 including the wavelength region considered to be effective for organic thin film observation.
It has good transmission characteristics for soft X-rays of
It has a transmission characteristic of hardly transmitting soft X-rays having a wavelength of 0 nm or more. Therefore, by combining with an Al thin film filter, the soft X
Only lines can be extracted.

When a polypropylene thin film is used, its thickness is preferably 1 to 5 μm. 1μ thickness
When it is less than m, the amount of soft X-rays absorbed is small, and soft X-rays in the wavelength region to be absorbed are transmitted. When the film thickness is 5
If the thickness is more than μm, the amount of soft X-rays absorbed increases, and soft X-rays of a wavelength desired to be transmitted are not transmitted.

If the main purpose is to observe a living body, a thin film made of an inorganic material may be used as a filter. In that case, it is preferable to use silicon nitride (Si ₃ N ₄ ) as the thin film. The transmission characteristic of a thin film of silicon nitride (Si ₃ N ₄ ) with respect to soft X-rays is hardly transmitted with respect to soft X-rays of 10 nm or less and 20 nm or more, so that a necessary soft X-ray region exists within this range. This is because it becomes an effective filter. Further, it has a transmittance peak near a wavelength of 13 nm. Therefore, soft X-rays near 13 nm can be extracted by removing X-rays in the visible light region with a metal thin film.

The above-described soft X-ray filter generally includes an X-ray source, X-ray detection means for measuring the intensity of X-rays emitted from the X-ray source, the X-ray source and the X-ray source. Soft X-ray having wavelength selecting means disposed between the X-ray detecting means
It can be used in line measuring devices. For example, the above-mentioned soft X-ray filter is used for the wavelength selecting means. In such an apparatus, unnecessary wavelength components are removed from the X-rays emitted from the X-ray source by the soft X-ray filter, so that the soft X-rays detected by the X-ray detecting means are soft in a narrow wavelength range. Only X-rays are detected. Where X
As a ray generation source, any source such as a laser beam source, a synchrotron beam (SOR beam), and an X-ray tube may be used.
However, X-rays in the soft X-ray region may be irradiated. The X-ray detecting means used in the soft X-ray measuring device includes MC
P (micro channel plate), scintillation counter, imaging plate, X-ray CCD camera,
Any film such as a special film (such as a holotest film), a semiconductor detector, and a special photographic dry plate may be used.

In a further preferred embodiment of the above-mentioned apparatus, it is preferable to dispose a reflecting mirror coated with gold or platinum between the X-ray source and the X-ray detecting means. This is because a reflecting mirror coated with gold or platinum can remove soft X-rays having a short wavelength from the reflected soft X-rays when the incident light is incident at a nearly horizontal incident angle (oblique incident angle). In this case, the oblique incidence angle of the soft X-ray is 2 to
It is set in the range of 10 °. If it is not within this range, the required soft X-rays will not be reflected. Also, 2
To remove soft X-rays of nm or less, the oblique incidence angle is 4 °.
It is good to set to about. Such a reflection mirror may be provided between the X-ray source and the soft X-ray filter, or may be provided between the soft X-ray filter and the X-ray detecting means.

The wavelength selecting means used in the above-described device may be constituted by a metal thin film and a reflecting mirror formed of a multilayer film of molybdenum (Mo) and silicon (Si). Soft X after reflection by multilayer film of Mo and Si
Since a plurality of soft X-rays reflected at the boundary between Mo and Si and soft X-rays reflected at the surface of the multilayer film interfere with each other, if the film thickness and the incident angle are adjusted, the soft X-rays having a predetermined wavelength can be obtained. Can interfere with lines and cancel. Therefore, when the wavelength selecting means is configured by combining the reflection mirror of the multilayer film of Mo and Si with the metal thin film, only soft X-rays of a specific wavelength can be transmitted.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.

Soft X-ray wavelength 4 nm, which is advantageous for observation of organic thin films
A wavelength selection filter for selecting a range of ７7 nm was created. First, an Al thin film was used as a metal thin film, and a polypropylene thin film was used as a nonmetallic thin film. For comparison, a single-layer filter containing only an Al thin film and a single-layer filter containing only polypropylene were also prepared. By changing the thickness of the above three types of filters,
The soft X-ray transmittance of each filter was measured.

FIG. 2 shows the transmission characteristics of a single-layer filter having only an Al thin film for soft X-rays. The thickness is 0.05μ
m, 0.2 μm, 1 μm, and 5 μm. In FIG. 2, the horizontal axis represents the soft X-ray wavelength, and the vertical axis represents the soft X-ray transmittance at each wavelength. As is clear from FIG. 2, in the case of a single-layer filter comprising only an Al thin film, the transmittance decreases up to a wavelength of about 10 nm, the transmittance is almost flat from the wavelength 10 nm to the point A of 17 nm, and the wavelength is 17 μm. When it exceeds, the transmittance increases sharply. In the range exceeding 17 nm, the transmittance gradually decreases as the wavelength increases.
As a result, the Al thin film has soft X-rays having a wavelength of 10 μm or less,
It was found that soft X-rays of 17 μm or more were transmitted. When the thickness of the Al thin film is 0.05 μm or less, the wavelength 1
Even in the range of 0 to 17 μm, the transmittance was about 20% or more. When the thickness of the Al thin film is 1 μm or 5 μm, even soft X-rays having a wavelength of 4 to 7 μm are absorbed and the transmittance is 0 μm.
Met. Therefore, the film thickness of Al is 0.05 to 0.1.
It has been found that it is better to select in the range of 2 μm.

FIG. 3 shows the soft X-ray transmittance of a single-layer filter made of only polypropylene. The film thickness is 0.5 μm, 1
μm, 5 μm, and 10 μm. In FIG. 3, the soft X is plotted on the horizontal axis.
The vertical axis represents the soft X-ray transmittance at each wavelength. As is clear from FIG. 3, in the case of a single-layer filter made of polypropylene alone, the transmittance sharply decreases up to a wavelength of about 4 nm, and the transmittance sharply increases at a wavelength of 4 μm. Decreases to a wavelength of 20 nm
As a result, almost no soft X-rays were transmitted. When the thickness of the polypropylene thin film is 0.5 μm or less, the wavelength is 10 to 10 μm.
Even in the region of 20 nm, the transmittance was a considerably high value. When the thickness of the polypropylene thin film was 10 μm or more, the amount of absorbed soft X-rays was large, and the transmittance was considerably low even at a wavelength of 4 to 7 nm. Therefore, it was found that the thickness of the polypropylene thin film is preferably selected in the range of 1 to 5 μm.

From the above results, it can be seen that the Al thin film has a thickness of 0.05 to
A 0.2 μm-thick polypropylene thin film was selected in the range of 1 to 5 μm to prepare a soft X-ray filter according to the present invention. FIG. 1 shows the soft X-ray transmittance of a filter in which an Al thin film and a polypropylene thin film are stacked. The film thickness is (Al
(Thin film 0.05 μm, polypropylene 1 μm), (Al thin film 0.2 μm, polypropylene 1 μm), (Al thin film 0.05 μm, polypropylene 5 μm), (Al thin film 0.2 μm, polypropylene 5 μm). In FIG. 1, the horizontal axis represents the soft X-ray wavelength, and the vertical axis represents the soft X-ray at each wavelength.
Indicates the transmittance of the line. As is clear from FIG. 1, it was found that a filter in which an Al thin film and a polypropylene thin film were stacked had good transmittance at a wavelength of 4 to 7 nm, and hardly transmitted soft X-rays at other wavelengths. .

Next, a suitable direct soft X-ray measuring apparatus which can use such a soft X-ray filter was constructed. Hereinafter, the structure of the soft X-ray measurement device will be described with reference to FIG.

First, the soft X-ray measuring apparatus shown in FIG. 4 includes a first vacuum chamber 20 in which an X-ray source 10 is disposed, and an X-ray emitted from the light source 10 adjacent to the first vacuum chamber 20. Has a second vacuum chamber 22 in which the X-ray detecting means 17 for detecting the The first vacuum chamber 20 is provided with a window 12 for guiding the X-rays 16 emitted from the X-ray source 10 to the second vacuum chamber 22. 1
The X-ray 16 emitted from 0 is guided.
In the second vacuum chamber 22, a reflection mirror 14 that reflects the X-rays 16 is provided, and a wavelength selection unit 15 is provided between the reflection mirror 14 and the X-ray detection unit 17.

The operation of the soft X-ray measuring apparatus thus configured will be described. As the wavelength selecting means 15, a filter for a soft X-ray of the present invention (Al thin film 0.2 μm, polypropylene 4 μm) was used. X-rays 16 emitted from the X-ray source 10 enter the second vacuum chamber 22 through the window 12 and are reflected by the reflection mirror 14. For the reflection mirror 14, a reflection-type condensing optical element on which gold was deposited was used. The light was incident obliquely at an angle of incidence of 4 ° on the reflection mirror 14. The incident angle was 4 °. FIG. 5 shows the reflectance of the reflection mirror 14 when the oblique incident angle is 4 °. In FIG. 5, the horizontal axis represents the wavelength, and the vertical axis represents the reflectance for soft X-rays. FIG.
As can be seen from FIG.
Below, it was found that there was almost no reflection. In addition, 3-1
The reflectivity gradually increased in the range of 0 nm, and became about 80% in the range of 10 nm or more. Therefore, the X-rays 18 reflected by the reflection mirror 14 hardly include soft X-rays of 2 nm or less.

The X-ray 18 reflected by the reflection mirror 14 is
The light enters the soft X-ray filter 15 (Al thin film 0.2 μm, polypropylene 4 μm), and X-rays having a predetermined component wavelength are removed. The transmittance of the soft X-ray filter 15 is shown in FIG.
Shown in As is clear from FIG. 6, the wavelength region having a transmittance of 1% or more is only soft X-rays having a wavelength of 2 nm or less and a wavelength in the range of 4 to 7 nm. The X-rays 18 incident on the soft X-ray filter 15 are already reflected by the reflection mirror 14 into soft X-rays of 2 nm or less.
Since the line component has been removed, the soft X-ray filter 15
X-rays 19 that have passed through are only soft X-ray components in the range of 4 to 7 nm. The X-ray 19 is detected by the X-ray detection unit 17. The transmittance of the soft X-ray filter 15 in the long wavelength region of the soft X-ray filter 15 is not shown in FIG. 6, but the transmittance of the soft X-ray filter 15 in this region is substantially zero.

The intensity of the soft X-ray detected by the X-ray detecting means 17 will be described with reference to FIGS. FIG. 7 is a bar graph showing the soft X-ray intensity when the filter is not provided in the wavelength selecting means 15 in the above-described apparatus, when the Al filter is provided, and when the soft X-ray filter of the present invention is provided. Are shown in comparison. When the light of the soft X-ray source 10 directly reaches the X-ray detecting means 17 without disposing a filter, the soft X-ray intensity is about 50,000 A.U, but about 5000 A.U through the Al filter. When the soft X-ray filter of the present invention is provided, the temperature is further reduced to about 2000 A.U. This is because the intensity of the soft X-rays is high when no filter is provided or when only the Al filter is used, since soft X-rays in unnecessary wavelength regions are detected. FIG. 8 shows the X-rays detected by the X-ray detection means 17.
The intensity of each wavelength component of the line intensity is shown. The horizontal axis shows the wavelength of the soft X-ray, and the vertical axis shows the intensity of the soft X-ray. FIG. 8 shows the case where the soft X-ray filter of the present invention is used as the wavelength selecting means 15 and the wavelength selecting means 15 is only an Al filter, and the case where no filter is provided. In the case of an Al filter or when no filter is provided, 1
Although light with a wavelength of 8 nm or more is also transmitted, FIG. 8 shows only the range of 3 to 7 nm for comparison. FIG.
As is clear from the above, when the Al filter is provided or when the soft X-ray filter of the present invention is provided, the soft X-ray intensity gradually decreases as compared with the case where no filter is provided. However, the wavelength range of transmitted soft X-rays becomes narrow. As described above, in the above-described apparatus, the intensity of the soft X-rays detected by the X-ray detection unit 17 by the reflection mirror 14 and the soft X-ray filter of the present invention is reduced.
The wavelength of soft X-rays detected in the above was only in the range of 4.5 to 6 nm, and only soft X-rays of a specific wavelength could be used.

Next, a description will be given of an example of the apparatus shown in FIG. 4 in which the wavelength selecting means 15 is used for a living body observation using a filter in which Al is deposited on silicon nitride. Wavelength selection means 15
The other parts other than the above are the same, and the description thereof will be omitted.

To examine the transmission characteristics of a filter in which Al is deposited on silicon nitride, first, silicon nitride (Si ₃ N ₄ )
The transmission characteristics were examined by changing the thickness of the film. FIG. 9 shows the result. FIG. 9 shows the X-ray wavelength on the horizontal axis and the transmittance on the vertical axis. The case where the thickness of the silicon nitride is 0.2 μm is shown on the left scale (one scale of 5%).
The case of μm is shown as a scale on the right side (0.02% per scale). As is apparent from FIG.
It was found to have a transmittance peak at a wavelength of 3 nm. When the thickness of the silicon nitride film was 0.2 μm, the transmittance at a wavelength of 13 nm was large, but the light was also transmitted through a wavelength range of around 24 nm. Therefore, it was found that if the film thickness was too small, the wavelength range to be transmitted would be widened, and the effect as the wavelength selection means could not be obtained.
When the film thickness is 1 μm, the transmittance is 0.04% at the maximum.
It turned out that it was hardly transmitted. For this reason,
It has been found that the film pressure of the silicon nitride film is preferably about submicron. Therefore, the film pressure of the silicon nitride film was set to 0.2 μm.

Next, a thin film of silicon nitride of 0.2 μm
The transmittance of the filter on which the thin film was deposited was examined. Specifically, (Al thin film 0.01 μm, silicon nitride (Si ₃
N ₄ ) 0.2 μm). The result is shown in FIG.
Shown in The horizontal axis shows the wavelength, and the vertical axis shows the transmittance. As is clear from FIG. 10, when the Al thin film is set to 0.01 μm, the wavelength region of 2.2 to 4.4 nm, which is the window region of water, and the wavelength region of 5 to 12 nm which adversely affects observation are included. Soft X-rays are hardly transmitted. In the case of observing a living body, there is no problem because a wavelength component of 12 nm or more does not affect the observation.

The Al thin film is made of another metal thin film such as Be, Cu, Au, Mo, Ni, Pt, Ag, W, T
It can be replaced by a metal thin film of i, V, Cr, Mn, Sc, Co, Zn, Fe, etc. That is, if the thickness of these metal thin films is set to about 0.01 μm as in the present embodiment, it is possible to select a soft X-ray having a wavelength of 4 nm or less, which is optimal for living body observation.

Next, the configuration of a reflection type soft X-ray measuring apparatus according to another embodiment of the present invention will be described with reference to FIG.

First, in the reflection type soft X-ray measuring apparatus, an X-ray source 10 is disposed inside a first vacuum chamber 20, and a window provided at a boundary between the first vacuum chamber 20 and the second vacuum chamber 22. 12 to X
The same is true in that the X-rays of the X-ray source 10 are guided into the second vacuum chamber 22 and the X-ray detector 17 disposed in the second vacuum chamber 22 detects soft X-rays. However, as the wavelength selecting means 15 disposed between the X-ray source 10 and the X-ray detecting means 17, the filter shown in FIG. In the reflection type soft X-ray apparatus, the Al filter 24 and the Mo / Si
The difference is that the multi-layer mirror 25 is used. Hereinafter, differences will be mainly described.

The Al filter 24 is composed of only a metallic thin film, and its transmission characteristics are as shown in FIG. The thickness of the Al thin film was 0.2 μm. In the embodiment of FIG. 11, the Al thin film only plays a role of removing X-rays in the longer wavelength region, as described later, and therefore, as in the case of using the silicon nitride thin film described above, Be, C
u, Au, Mo, Ni, Pt, Ag, W, Ti, V, C
It can be replaced by a metal thin film of r, Mn, Sc, Co, Zn, Fe, etc. In order to increase the intensity of soft X-rays detected by the X-ray detecting means 17, it is preferable that the thickness of the soft X-ray filter is formed as thin as possible.

The Mo / Si multilayer mirror 25 is composed of Mo and S
It is formed by periodically laminating i with a predetermined thickness. Soft X-rays can be selected with such a multilayer film because Mo
This is because a plurality of soft X-rays reflected at each boundary between the soft X-rays and the soft X-rays reflected at the surface interfere with each other, so that soft X-rays of a predetermined wavelength can be canceled out by interference. Therefore,
By appropriately adjusting the thickness of each layer of Mo and Si and the angle of incidence on the multilayer mirror, a soft X-ray having a desired wavelength can be selected.

More specifically, the Mo / Si multilayer mirror 25
A multilayer mirror having 6 nm of Mo and 9 nm of Si and deposited at a cycle of 15 nm was used. The transmission characteristics of the Mo / Si multilayer mirror 25 will be described. The angle of incidence of X-rays on the Mo / Si multilayer mirror 25 was 45 °, but the incidence on the mirror surface was shallow (for example, an incident angle of 60).
(Degree), higher reflected X-ray intensity can be obtained.
FIG. 12 shows the reflection characteristics of the Mo / Si multilayer mirror 25. FIG. 12 shows the reflectance on the vertical axis and the wavelength on the horizontal axis. As can be seen from FIG. 12, according to the multilayer mirror, the reflectance has a peak of about 40% in the range of 17 to 20 nm, and the reflectance is low in other wavelength regions.

The operation of the soft X-ray measuring apparatus configured as described above will be described. The X-ray 16 emitted from the X-ray source 10 enters the second vacuum chamber 22 through the window 12 of the first vacuum chamber 20. This X-ray 16 is transmitted through an Al filter 24.
As a result, the X-rays in the longer wavelength region are reflected and removed.

The light 18 transmitted through the Al filter 24 is
The light is reflected by the Mo / Si multilayer mirror 25. As described above, it was found that the characteristic of the reflective Mo / Si multilayer mirror 25 has a peak at a wavelength of 17 to 20 nm and has a reflectance of about 30 to 46%.

Therefore, the Mo / Si multilayer mirror 25
In the soft X-ray 19 after being reflected by the above, the intensity of the soft X-ray having a wavelength of 18 to 20 nm increased. In this case, the X-ray detecting means 17
FIG. 13 is a bar graph showing the intensity of soft X-rays reaching. For comparison, a case where only the Al filter 24 is provided and a case where the intensity of X-rays directly emitted from the X-ray generation source 10 is detected by the X-ray detection unit 17 are also shown. As is clear from this figure, when the X-rays of the X-ray source 10 directly reach the X-ray detecting means 17 without passing through a filter, the soft X-ray intensity becomes almost zero.
50000A.U, but 10000A.U through Al filter
In the case where the Al filter and the Mo / Si multilayer film reflection mirror are combined, it is further reduced to about 5000 AU. As described above, the intensity of the soft X-ray reaching the X-ray detecting means 17 is reduced by the filter and the reflection mirror.
As shown in (1), direct light includes soft X-rays of a wide range of wavelengths, but only soft X-rays of a specific wavelength around 18 nm could be selectively transmitted through a filter and a reflection mirror.

As described above, in the reflection type soft X-ray detecting device described above, the Mo / Si multilayer film mirror 25 is a Mo / Si multilayer film filter to select soft X-rays in the wavelength range of 18 to 20 nm. I was able to.

[0042]

As described in detail above, the soft X according to the present invention
With the X-ray filter and the soft X-ray measuring device, only the soft X-rays in a specific range could be selected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in transmittance for soft X-rays when the thickness of a wavelength selection filter composed of a multilayer film of Al and polypropylene according to an embodiment of the present invention is changed.

FIG. 2 is a graph showing the transmittance of an Al thin film to soft X-rays when the thickness of the Al thin film is changed.

FIG. 3 is a graph showing the transmittance of a thin polypropylene film to soft X-rays when the thickness of the polypropylene film is changed.

FIG. 4 is a drawing showing a schematic configuration of a direct soft X-ray measuring apparatus according to one embodiment of the present invention.

FIG. 5 is a view showing a reflectance characteristic of a reflection type condensing optical element on which gold is deposited, with respect to soft X-rays.

FIG. 6 is a view showing the soft X-ray transmittance of a wavelength selective filter comprising a multilayer film of Al and polypropylene provided in the direct type soft X-ray measuring device of FIG.

7 is a drawing showing soft X-ray intensities detected by X-ray detecting means of the direct type soft X-ray measuring apparatus of FIG. 4 when various filters are provided.

8 is a drawing showing the wavelength dependence of the soft X-ray intensity detected by the X-ray detecting means of the direct type soft X-ray measuring device of FIG. 4 when various filters are provided.

FIG. 9 is a view showing the transmittance of a multilayer film of Al and silicon nitride according to the present invention with a changed film thickness to soft X-rays.

FIG. 10 is a graph showing transmittance of silicon nitride with respect to soft X-rays.

FIG. 11 is a drawing showing a schematic configuration of a reflection type soft X-ray measuring apparatus according to one embodiment of the present invention.

FIG. 12 is a diagram showing the reflectance characteristics of a Mo / Si multilayer film with respect to soft X-rays.

FIG. 13 is a drawing showing soft X-ray intensities detected by X-ray detecting means of the reflection type soft X-ray measuring apparatus of FIG. 11 when various filters are provided.

FIG. 14 is a drawing showing the wavelength dependence of the soft X-ray intensity detected by the X-ray detecting means of the reflection type soft X-ray measuring device of FIG. 11 when various filters are provided.

FIG. 15 is a graph showing the transmittance of a metal thin film to soft X-rays.

FIG. 16 is a view showing the transmittance of a nonmetallic thin film to soft X-rays.

[Explanation of symbols]

 10. Soft X-ray source 12 Window 14. Reflection mirror 15. Wavelength selecting means 17 X-ray detecting means 20 First vacuum chamber 22 Second vacuum chamber 24 Al filter 25 ..Mo / Si multilayer mirrors

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Mase 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Atsushi Sakata 2 Toyota Town, Toyota City, Aichi Prefecture Toyota Max Corporation ( 72) Inventor Yasuhiko Nishimura 2nd Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Max Co., Ltd.

Claims (10)

[Claims] At least one of a metallic thin film and a nonmetallic thin film having different soft X-ray transmission characteristics from the metallic thin film.
A soft X-ray filter characterized by being constructed by laminating two types of thin films. 2. A soft X-ray according to claim 1, wherein said metallic thin film is an Al thin film.
Line filter. 3. The soft X-ray filter according to claim 2, wherein said non-metallic thin film is a thin film of a polymer material. 4. The soft X-ray filter according to claim 1, wherein the non-metallic thin film is a silicon nitride thin film. 5. The soft X-ray filter according to claim 3, wherein the Al thin film has a thickness of 0.01 to 0.2 μm. 6. The soft X-ray filter according to claim 3, wherein the thin film of the polymer material is a thin film of polypropylene. 7. The soft X-ray filter according to claim 6, wherein said polypropylene thin film has a thickness of 1 to 5 μm. 8. An X-ray source, X-ray detecting means for measuring the intensity of X-rays emitted from the X-ray source, and an X-ray source disposed between the X-ray source and the X-ray detecting means. 8. A soft X-ray measuring apparatus, comprising: a wavelength selecting unit, wherein the wavelength selecting unit is the soft X-ray filter according to claim 1. 9. The soft X-ray measuring apparatus according to claim 8, wherein a reflecting mirror coated with gold or platinum is further provided between the light source and the soft X-ray detecting means. Characteristic soft X-ray measurement device. 10. An X-ray source, X-ray detecting means for measuring the intensity of X-rays emitted from the X-ray source, and an X-ray source disposed between the X-ray source and the X-ray detecting means. A soft X-ray measuring device, comprising: a metal thin film; and a reflection mirror formed of a multilayer film of Mo and Si.