JP3923180B2 - X-ray optical element and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical element for X-rays and a method for producing the same.
[0002]
[Prior art]
X-rays exhibit high transmittance for many substances because of their short wavelength. By utilizing this feature, X-rays have been used for medical diagnosis and structural defect detection. Recently, with the need for lithography technology with higher resolution in the semiconductor industry, among the currently used light sources, X-rays with shorter wavelengths than the shortest excimer laser are used. Lithography technology is in the process of development.
[0003]
By the way, a dielectric material such as glass or crystal that is usually used in the visible or infrared wavelength range has a very low refractive index in the X-ray wavelength range and cannot be used as an optical element such as a lens. Further, the refractive index of the metal is similarly reduced, and cannot be used as a normal reflecting mirror in the X-ray wavelength region.
[0004]
Therefore, in the case of glazing incidence where a light ray is incident on a material at an extremely large angle close to 90 degrees, a glazing incidence optical system utilizing the fact that a high reflectance is obtained, and angstrom order of two or more different materials. A multilayer optical system constituted by laminating a large number of extremely thin films or a special optical system such as a zone plate is used to collect and reflect X-rays. However, these optical systems are very expensive because they are complex in construction, require very fine adjustments, and the manufacturing process is very complicated.
[0005]
Therefore, as an alternative to an optical system having these complicated structures, lobster eye optics using a capillary optical element formed by bundling a plurality of small glass capillaries and a glass plate having a plurality of pores It has been proposed and studied to use the element as an X-ray condensing or collimating optical system. In these optical elements, light rays are incident on the inner wall surface of the pore at a very large angle and propagate while repeating reflection on the inner wall surface.
[0006]
[Problems to be solved by the invention]
However, in the conventional optical element composed of ordinary quartz glass or pyrex glass, the imaginary part of the complex refractive index of the glass in the X-ray region is small, so that even in the case of glazing incidence at a very large incident angle, the reflectance Is not so large, and part of the energy of the X-ray is absorbed or transmitted through the inner wall, resulting in a decrease in the efficiency of the optical element.
[0007]
In order to make up for this drawback, there is an example in which an optical element is configured using lead glass exhibiting a relatively high reflectivity, but the effect is not so great and a significant increase in efficiency cannot be brought about. There is also an attempt to construct an optical element using a metal thin tube such as nickel that exhibits a very high reflectance, but there is a relatively large surface roughness on the inner wall of the metal thin tube, resulting in scattering loss. However, the efficiency as an optical element is reduced, and practical application is difficult.
[0008]
Accordingly, an object of the present invention is to provide a highly efficient X-ray optical element that solves the above-described problems, has a simple structure, and can be manufactured at low cost, and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is an optical element made of glass having a plurality of pores, and a thin film of metal is formed on the inner wall of the pores. An element is provided.
[0010]
Here, the metal may be gold, silver, copper, molybdenum, nickel, cobalt, beryllium, or aluminum.
[0011]
Further, the X-ray optical element manufacturing method of the present invention is a chemical vapor deposition method in which a vapor of a metal organic compound is allowed to flow into the pores of an optical element made of glass having a plurality of pores. A method for manufacturing an optical element for X-rays, comprising forming a metal thin film on an inner wall surface of a hole.
[0012]
And if it is such an X-ray optical element of this invention, it has a simple structure and can comprise a highly efficient X-ray optical element which can be manufactured at low cost.
[0013]
Further, according to the method for manufacturing an X-ray optical element of the present invention, a uniform metal thin film can be formed on the inner walls of a plurality of pores. Moreover, even in a wide wavelength range from soft X-rays to hard X-rays, it is possible to improve the reflectivity on the inner wall by appropriately selecting various metal materials, and it is possible to manufacture highly efficient optical elements. is there. Since the surface of the metal thin film to be generated can be made to be a very smooth surface in accordance with the smoothness of the glass surface, it is possible to manufacture an optical element with small additional loss due to scattering even for X-rays. In the manufacturing method of the present invention, since the raw material is allowed to flow into the pores as vapor, it is possible to simultaneously form films in a plurality of extremely minute pores, which can be applied to the manufacture of optical elements of various shapes. Is possible.
[0014]
[Embodiments of the Invention]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an embodiment of the optical element of the present invention. As shown in the figure, a plurality of glass capillary tubes 1A, a metal thin film 1B provided on the inner wall of the capillary tube 1A, a hollow region 1C defined by the inner wall of the metal thin film 1B, and a plurality of capillary tubes 1A The X-ray optical element 1 is formed by a jacket 1D for bundling.
[0015]
FIG. 2 is a perspective view showing an embodiment and an enlarged view 2A at the end face when the optical element of the present invention is used as a collimator. The X-ray optical element 2 is formed by bundling a plurality of glass capillary tubes 1A and fusing them together to form a tapered shape. A metal thin film 1B is formed on the inner surface of the capillary tube 1A.
[0016]
FIG. 3 is an explanatory diagram of the function of the collimator optical element 2. When X-rays 4 generated radially from an X-ray source 3 such as an X-ray tube enter the collimator optical element 2, the X-rays enter the pores of the capillary tube, and after being repeatedly reflected on the inner wall, X-rays 5 are emitted from the optical element 2.
[0017]
FIG. 4 is an example of an embodiment in which the X-ray optical element of the present invention is used as a lens. The X-ray lens element 6 is configured by bundling and fusing a plurality of capillary tubes and forming a metal thin film on the inner surface thereof.
[0018]
FIG. 5 is an explanatory view showing the function of the lens element 6. When X-rays 4 having a radial spread are incident on the lens element 6, they are reflected by the inner surface of the capillary tube and are emitted from the lens element. As shown in FIG. 5, since the emitted X-rays 5 are condensed, the element 6 functions as a lens.
[0019]
In the explanatory views shown in FIGS. 3 and 5, X-rays are reflected on the inner surface of the capillary tube, but the metal thin film 1B has a function of increasing the reflectance at that time and improving the transmission efficiency of the entire device. Therefore, it is desirable that the metal thin film 1B exhibits a high reflectance at the X-ray wavelength used. In general, since the reflectance of metal varies depending on the wavelength, it is necessary to form a metal of an appropriate material according to the X-ray wavelength used. Further, it is sufficient that the thickness of the metal thin film 1B is thicker than the skin depth of the wavelength to be used.
[0020]
Further, the cross-sectional shape of the pore 1C of the X-ray optical element 1 may be a hexagon, a quadrangle, or the like in addition to a circle. Although the manufacturing process is complicated, the overall throughput of the device is improved by using hexagons, squares, and the like.
[0021]
Next, an example of the manufacturing method of the hollow waveguide of this invention is demonstrated using FIG. The vapor gas of the organic metal raw material is caused to flow into the glass capillary 1A. At that time, depending on the raw material to be used, it may be mixed with an inert gas such as argon or helium or a gas such as oxygen, nitrogen or hydrogen and flowed into the glass capillary 1A.
[0022]
On the downstream side of the glass capillary 1A, a pump 7 that can obtain a high vacuum such as a turbo molecular pump or an oil diffusion pump and a pump 8 that can obtain a large displacement such as a mechanical booster pump are arranged. Before the raw material vapor is introduced, the high vacuum pump 7 is driven to remove the air and the like inside the glass capillary 1A, and the pressure in the pipe is set to a vacuum state of 10 ⁻³ Pa or less. Thereafter, when the raw material vapor is introduced, the pump is switched to the large displacement pump 8 and the flow rate of the raw material and the conductance of the valve are adjusted so that the pressure becomes 10 to 1000 Pa.
[0023]
Also, as a pre-treatment for metal film formation, when a vapor such as titanium tetrachloride is passed through the glass capillary 1A, the inner surface of the pipe is activated, and a metal thin film can be formed at a low temperature, forming a metal thin film with an extremely smooth surface. become able to. In this embodiment, the valve of the container 9 containing titanium tetrachloride is opened under a pressure of 10 to 1000 Pa, and the generated vapor is allowed to flow into the glass capillary 1A for about 1 to 3 minutes.
[0024]
Then, after maintaining a vacuum state for about 30 to 60 minutes, the raw material vapor is caused to flow into the glass capillary 1A. In this state, the pie glass capillary 1A is heated to 80 to 500 ° C. using a heating mechanism 10 such as an annular electric furnace, thereby forming a metal thin film on the inner surface of the glass capillary 1A. If the temperature at this time is too high, the film formation rate becomes too high and the surface roughness of the metal thin film is large. For this reason, it is important to set the minimum necessary temperature.
[0025]
【The invention's effect】
In short, according to the present invention, the following excellent effects are exhibited.
[0026]
(1) The transmission efficiency can be made extremely high by selecting an appropriate metal for the wavelength used.
[0027]
(2) Elements having various shapes can be configured, and optical elements having various functions can be formed.
[0028]
(3) Excellent in mass productivity and can be produced at low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a perspective view and an enlarged end view of a collimator optical element.
FIG. 3 is an explanatory diagram regarding functions of a collimator optical element;
FIG. 4 is a perspective view of a lens optical element.
FIG. 5 is an explanatory diagram of a lens optical element.
FIG. 6 is an explanatory diagram of a method for manufacturing an optical element of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 X-ray optical element 1A Glass capillary 1B Metal thin film 1C Hollow area 2 Collimator optical element 2A End face enlarged view 3 X-ray source 4 Incident X-ray 5 Outgoing X-ray 6 Lens optical element 7 High vacuum pump 8 Large displacement pump 9 Titanium chloride Container 10 heating mechanism

Claims (1)

X-ray optics that allows vapors of metal organic compounds to flow into the pores of optical elements composed of glass with multiple pores, and to form a thin metal film on the inner wall of the pores by chemical vapor deposition A method of manufacturing an optical element for X-rays, wherein titanium tetrachloride vapor flows into the glass pores as a pretreatment for forming a metal thin film and activates the glass surface. .

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