JP3052271B2 - X-ray mirror making method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an X-ray mirror for use in reflecting, dispersing, condensing, etc., radiation including X-rays generated in a synchrotron apparatus.

[0002]

2. Description of the Related Art Synchrotron radiation (hereinafter referred to as "radiation") includes a wide wavelength range from hard X-rays to infrared rays generated when electrons accelerated to almost the speed of light by a synchrotron device are bent by a bending electromagnet. It is highly directional light. X-rays and vacuum ultraviolet components of synchrotron radiation have extremely high light intensity compared to other light sources, and are used to analyze and analyze the structure of materials, to form and etch films by photochemical reactions, and to transfer large amounts of submicron patterns at high speed. Application to line exposure and the like is being studied.

[0003] X-rays generated from a synchrotron device are flat beams spread in a horizontal direction from a light source point, and therefore, it is necessary to condense or convert them to parallel light in order to utilize them. Further, an image is formed or a wavelength range is dispersed. X-ray mirrors are widely and generally used as optical components that enable these.

FIG. 3 is a schematic view for explaining the structure of a conventional X-ray mirror, wherein 1 is an X-ray reflection film, 2 is an adhesion enhancing film, and 3 is a mirror substrate. In FIG. 1, platinum or gold is used as the X-ray reflection film 1, and quartz glass, SiC, aluminum or copper, or electroless nickel-plated aluminum or copper is used as the mirror substrate 3. The adhesion enhancement film 2 is used when the adhesion between the X-ray reflection film 1 and the mirror substrate 3 is insufficient, and chromium or the like is used.

References describing this type of technology include, for example, Tsukamoto et al., “Radiation Irradiation Damage of Soft X-ray Reflection Mirror”, 1990, Autumn, Proceedings of the 51st Annual Meeting of the Japan Society of Applied Physics. , 2nd volume, 501 pages, 28p-Y-5.

[0006]

In such an X-ray mirror, the refractive index of the reflection film is almost close to 1 in the X-ray region, and almost no reflectance can be expected at a normal incident angle as in the case of visible light. . Therefore, by utilizing the total reflection characteristic of the reflection film, the X-ray is incident on the mirror with the oblique incident angle set to 1 to 2 degrees. For this reason, a large X-ray mirror is required to effectively capture the emitted light. For example, when an X-ray mirror is installed near 3 m from the light source point, a plane mirror needs to have a length of about 30 to 40 cm, and a curved mirror needs to have a size of about 50 to 70 cm. Further, since the wavelength of X-rays is extremely shorter than that of visible light, it is required that the surface roughness is extremely small and the surface accuracy is excellent in order to provide an X-ray mirror with high reflectivity and high imaging performance. Therefore, the production of the X-ray mirror requires advanced processing technology in view of the required size and processing accuracy, and the production is time-consuming and expensive.

However, when such an X-ray mirror is used in a beam line utilizing radiation light or the like, it is inevitable that its performance will gradually deteriorate due to the influence of strong radiation light. For example, the reflective film may be peeled off due to the thermal load of synchrotron radiation,
Alternatively, a contaminant such as carbon adheres to the surface of the reflection film due to a reaction between the residual gas in the use atmosphere and the emitted light, thereby causing a decrease in reflectance and imaging performance. Therefore X
In a radiation light utilization apparatus using a line mirror, it is necessary to periodically replace the X-ray mirror in order to maintain its performance at a constant level, and it has been necessary to manufacture an expensive X-ray mirror each time.

An object of the present invention is to solve these problems, remove the X-ray reflection film with reduced performance from the X-ray mirror substrate, and form a new X-ray reflection film. An object of the present invention is to provide an X-ray mirror producing method capable of reproducing an X-ray mirror at low cost and in a short time.

[0009]

In order to achieve the above object, according to the present invention, a synchrotron device is used for reflecting, dispersing, condensing, etc., radiated light including X-rays and forming it on a substrate surface. In a method for producing an X-ray mirror in which a reflecting film to be formed is made of a heavy metal, (A) an X-ray mirror in which the reflecting film is formed on a substrate surface processed into a predetermined shape and flattened to a predetermined smoothness is used. (B) removing the reflective film by wet etching with a chemical agent while maintaining the smoothness of the substrate surface, when the performance of the reflective film is reduced due to use by exposure to synchrotron radiation; Forming a reflective film made of heavy metal on the substrate surface by a film forming method with a particle energy of 300 eV or less while maintaining the smoothness of the substrate surface. I do.

[0010]

The present invention is characterized in that the reflection film is once removed and formed again in the X-ray mirror used in the apparatus utilizing the radiated light, and the performance of the X-ray mirror can be maintained inexpensively in a short time. This is very different from the conventional X-ray mirror that is newly created when the performance is deteriorated in the cost and period required for replacement.

An X-ray mirror is a reflection mirror formed by forming a thin film of platinum or the like on a substrate surface flattened to a degree of smoothness of one or two atoms. The reflective film becomes dirty during use by being exposed to synchrotron radiation, and the reflectance is reduced. Therefore, in order to reproduce the X-ray mirror, the reflection film is removed. However, since the smoothness of the substrate surface is required to be on the order of one or two atoms, this smoothness is maintained. Conventionally, it has not been considered that only the reflection film can be removed while keeping the state.

In the present invention, by employing wet etching with a chemical, only the reflection film made of heavy metal is removed while maintaining the smoothness without etching the substrate surface at all. After the drying treatment of the substrate surface, a film forming method having a particle energy of 300 eV or less is employed for the subsequent formation of the reflective film. In this case, the particle energy is several kV
In the film formation method by the degree of ion beam assist etc.,
It is impossible to maintain the smoothness of the substrate surface because the substrate surface is affected by the high energy particles and etched, or the substrate material and the film material are mixed at the interface between the substrate and the film. On the other hand, according to a film forming method having a particle energy of 300 eV or less, such as a vacuum deposition method, a low-energy particle activates the substrate surface and forms a good-quality film while maintaining the smoothness of the substrate surface. Becomes possible. In addition, the reflection film formed quietly by such low-energy particles enables removal of only the reflection film by the wet etching at the time of mirror reproduction while maintaining the smoothness of the substrate surface in good condition. Even when the X-ray mirror is reproduced and used by repeatedly removing and forming the reflection film many times, good X-ray reflection characteristics can be maintained.

[0013]

FIG. 1 shows an embodiment of an X-ray mirror forming method according to the present invention. 4 is a mirror substrate made of quartz glass, 5 is an old adhesion-enhancing film, 6 is an old X-ray reflection film, 7 is a new adhesion-enhancing film, and 8 is a new X-ray reflection film. Quartz glass is shaped by precision cutting or grinding, and finally polished to form an X-ray mirror substrate 4. At this stage, surface accuracy and surface roughness required for the X-ray mirror are secured. Then X
An X-ray reflection film 6 is formed on the reflection surface of the line mirror substrate to form an X-ray mirror. Usually, a chromium film is formed on the substrate to a thickness of about 100 ° as the adhesion reinforcing film 5 to improve the adhesion.
Platinum film as X-ray reflection film on chromium film
It is formed about 0 °. The adhesion enhancement film 5 and the X-ray reflection film 6 are formed by a vacuum deposition method. The surface accuracy after forming the X-ray reflection film is almost the same as before the formation because the film thickness of the X-ray reflection film etc. is extremely thin, and the surface roughness is better than before the formation if the X-ray reflection film is formed under good conditions. Can be done.

If the device is continuously used as an X-ray mirror in a radiation light utilization device, the reflection film is peeled off due to a thermal load of the radiation light, or the surface of the reflection film is caused by a reaction between the residual gas in the use atmosphere and the radiation light. A contaminant such as carbon may be attached, thereby lowering the reflectance and the imaging performance.

The X-ray mirror whose performance has deteriorated removes the X-ray reflection film 6 and the adhesion enhancing film 5 from the mirror reflection surface. Removal is performed by wet etching using aqua regia. The surface accuracy and surface roughness after removal are almost the same as before removal.
FIG. 2 shows the X-ray reflection characteristics of the quartz glass substrate before and after the removal of the platinum reflection film. 9 is the X-ray reflection characteristic of the substrate before forming platinum,
Reference numeral 10 denotes the X-ray reflection characteristics of the substrate after removing the formed platinum. In general, the X-ray reflection characteristic is sensitively affected by the surface roughness and surface accuracy of the reflection surface, and the state of the reflection surface can be evaluated and judged from this characteristic. From FIG. 2, the X-ray reflectivity characteristic 9 before the formation of platinum and the X-ray reflectivity characteristic 10 after the removal of platinum show almost no change in the normally used oblique incidence angle range of 1 to 2 degrees. From this, it can be seen that even if the platinum of the X-ray reflection film is removed, the surface roughness and surface accuracy of the substrate reflection surface are hardly affected. The adhesion enhancement film 7 and the X-ray reflection film 8 are newly formed on the surface from which the old adhesion enhancement film and the X-ray reflection film have been removed, and are used again as an X-ray mirror. Here, the adhesion enhancement film and the X-ray reflection film formed after the removal need not be the same material as the old film, and may be another material.

Although the present invention has been described in detail with reference to the embodiments, the present invention is not limited to the above-described embodiments, and the mirror substrate and the X-ray mirror may be used without departing from the scope of the invention.
Of course, various changes can be made to the material of the line reflection film, the presence or absence of the adhesion enhancing film, the chemical used for removing the reflection film and the like. Further, in the above embodiment, the removal of the X-ray reflection film or the like is performed only once, but the present invention can be applied to the reproduction of an X-ray mirror in which the formation and removal of the reflection film are repeated many times.

[0017]

As described above, when the X-ray mirror of the present invention deteriorates due to strong radiation, the reflection film is removed once, the reflection film is formed again, and reproduction is performed. Therefore, it is possible to maintain the performance of the radiation light utilization apparatus using the X-ray mirror at low cost and in a short time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an X-ray mirror forming method according to the present invention.

FIG. 2 is a diagram showing X-ray reflection characteristics of a substrate before forming a reflective film according to the present invention and after removing the formed reflective film.

FIG. 3 is a configuration diagram of a conventionally used X-ray mirror.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... X-ray reflection film 2 ... Adhesion enhancement film 3 ... Mirror substrate 4 ... Mirror substrate made of quartz glass 5 ... Old adhesion enhancement film 6 ... Old X-ray reflection film 7 ... New adhesion enhancement film 8 ... New X-ray reflection film 9 ... X-ray reflection characteristics of substrate before formation of reflection film 10. X-ray reflection characteristics of substrate after removal of reflection film

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-359197 (JP, A) JP-A-63-113504 (JP, A) JP-A-64-73087 (JP, A) JP-A-2- 5525 (JP, A) JP-A-2-271625 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G21K 1/06 G02B 5/08

Claims (1)

(57) [Claims] 1. A method for producing an X-ray mirror which is used for reflection, spectroscopy, condensing, etc. of radiated light including X-rays generated by a synchrotron apparatus and whose reflection film formed on a substrate surface is made of a heavy metal. ) The performance of the reflective film is degraded by using an X-ray mirror having the reflective film formed on a substrate surface processed into a predetermined shape and flattened to a predetermined smoothness to synchrotron radiation. Then, the reflective film is removed by wet etching with a chemical agent while maintaining the smoothness of the substrate surface, and (b) subsequent drying treatment,
Forming a reflective film made of a heavy metal on the substrate surface by a film forming method with a particle energy of 300 eV or less while maintaining the smoothness of the substrate surface.