JP2008261650A - Soft x-ray filter and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress decrease in intensity and reduction of transmittance of a soft X-ray filter with preventing oxidation of a metal thin film used for the filter to extract a soft X-ray. <P>SOLUTION: This filter comprises: a frame-shaped supporting board 101 having an opening part 101a made of single crystal silicon; a frame-shaped thin film (supporting thin film) 102 formed on the main surface side of the supporting board 101, having an opening part 102a; a lower oxidation prevention layer 103 formed on the thin film 102; a filter layer 104 formed on the lower oxidation prevention layer 103; and an upper oxidation prevention layer 105 formed to cover the upper face of the filter layer 104. The filter layer 104 is constituted with the metal thin film transmitting soft X-ray. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a soft X-ray filter that targets light in the vacuum ultraviolet to soft X-ray region with a wavelength of 200 nm or less, and a method for manufacturing the same.

  Light from the vacuum ultraviolet to the soft X-ray region with a wavelength of 200 nm or less is applied to the industry due to the emergence of high-intensity light sources such as synchrotron radiation, laser plasma X-ray sources, or higher harmonic generation of lasers. Is highly expected. The light obtained from these light sources has a broad spectrum, but in many applications, a specific wavelength region in the light obtained from the light source is used, and a filter is used to extract the specific wavelength region. It is used.

  For example, when soft X-rays are used as a specific wavelength region, soft X-ray filters are used. The soft X-ray filter separates the required soft X-ray region light and vacuum ultraviolet light from the visible region from the broadband light obtained from the light source. In order to separate visible light that causes damage to optical elements in the soft X-ray region and vacuum ultraviolet rays that affect high-order light such as a diffraction grating spectrometer, it has a wide field of application in the field of soft X-ray optics.

  Conventionally, a metal thin film that transmits a specific wavelength region is used as such a filter (see Patent Document 1). Although a method using a filter is simple, since light in the soft X-ray region is very absorbed, it is necessary to make the thickness of the metal thin film as extremely thin as about 100 nm. As a method for producing a filter composed of such a metal thin film, a metal thin film is formed on a metal salt crystal as a base, and then the base metal salt is dissolved in water and removed. There is a way to scoop. There is also a method in which a metal thin film is formed on a membrane made of silicon nitride, and then the membrane is removed by dry etching.

JP 2002-168998 A

  However, as described above, after the process of manufacturing the filter and after the manufacturing, the surface of the formed metal thin film is oxidized, thereby significantly reducing the strength of the filter made of the metal thin film. There is also a problem that the transmittance of soft X-rays is reduced.

  The present invention has been made to solve the above-described problems. By preventing oxidation of a metal thin film used as a filter for extracting soft X-rays, the strength of the soft X-ray filter is reduced and the transmittance is reduced. The purpose is to be able to suppress the decrease of

  The soft X-ray filter according to the present invention is formed in contact with a filter layer made of a metal thin film that transmits soft X-rays formed on a support structure including an opening, and a lower surface of the filter layer on the support structure side. And a lower antioxidant layer formed in contact with the upper surface of the filter layer. Accordingly, the filter layer is sealed with the lower antioxidant layer and the upper antioxidant layer. In addition, the support structure should just be comprised from the support substrate provided with the opening part, and the support thin film provided on the support substrate and provided with the opening part.

  The metal may be selected from aluminum, zirconium, tin, magnesium, titanium, germanium, tantalum, rhenium, scandium, chromium, and yttrium. The lower antioxidant layer and the upper antioxidant layer may be selected from silicon, carbon, boron, and nitrides, carbides, fluorides thereof, gold, platinum, and ruthenium. In addition, the lower antioxidant layer and the upper antioxidant layer may be selected from metal nitrides, carbides, and fluorides.

  Moreover, the manufacturing method of the soft X-ray filter according to the present invention includes a first step in which a support thin film is formed on the main surface of the support substrate, and an opening that penetrates the support substrate from the back surface of the support substrate. A second step of forming a lower layer, a third step of forming a lower layer anti-oxidation layer on the support thin film, and a filter layer made of a thin metal film that transmits soft X-rays. A fourth step in which the upper antioxidation layer is formed in contact with the filter layer, and a support thin film by selectively removing the support thin film. And a sixth step of forming an opening through which the lower antioxidant layer is exposed.

  As described above, according to the present invention, the filter layer made of a metal thin film that transmits soft X-rays, the lower antioxidant layer formed in contact with the lower surface of the filter layer, and the upper surface of the filter layer are in contact with each other. Since the upper anti-oxidation layer is formed, the filter layer is sealed by the lower anti-oxidation layer and the upper anti-oxidation layer, so that the filter layer is prevented from being oxidized, and the soft X The excellent effect that the fall of the intensity | strength of a line filter and the reduction | decrease of the transmittance | permeability can be suppressed is acquired.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a configuration of a soft X-ray filter in an embodiment of the present invention. This soft X-ray filter includes, for example, a frame-shaped support substrate 101 made of single crystal silicon and having an opening 101a, and a frame-shaped thin film (support thin film) formed on the main surface side of the support substrate 101 and having an opening 102a. ) 102, the lower antioxidant layer 103 formed on the thin film 102, the filter layer 104 formed on the lower antioxidant layer 103, and the upper antioxidant layer formed so as to cover the upper surface of the filter layer 104 Layer 105. The filter layer 104 is composed of a metal thin film that transmits soft X-rays.

  In this configuration example, a laminated film composed of a lower antioxidant layer 103, a filter layer 104, and an upper antioxidant layer 105 is stretched on a frame-like support structure having an opening made of a support substrate 101 and a thin film 102. It is in a state that has been. Further, the filter layer 104 is sealed with the lower antioxidant layer 103 and the upper antioxidant layer 105. The laminated film does not need to be stretched as long as it is installed in the opening of the support structure or the like.

  Next, the soft X-ray filter of the present invention configured as described above will be described in more detail using examples.

[Example 1]
First, the soft X-ray filter of Example 1 will be described. In the soft X-ray filter of Example 1, the thin film 102 is made of silicon nitride (SiN _x ), the lower antioxidant layer 103 and the upper antioxidant layer 105 are made of silicon carbide (SiC), and the filter layer 104 is made of aluminum. (Al).

  Hereinafter, the manufacturing method of the soft X-ray filter of the present Example 1 is demonstrated using process drawing of FIG. 2 (a)-FIG.2 (e), FIG.3 (f), and FIG.3 (g). First, a support substrate 101 made of single crystal silicon having a main surface of (100) is prepared, and silicon nitride is deposited on the main surface and back surface of the support substrate 101 by a well-known CVD (Chemical Vapor Deposition) method. . As a result, as shown in FIG. 2A, a thin film (supporting thin film) 102 and a thin film 112 having a thickness of about 200 nm are formed on the main surface and the back surface of the supporting substrate 101.

Next, as shown in FIG. 2B, a positive type photoresist film 201 that is sensitive to ultraviolet rays is formed on the thin film 112 on the back surface side. Next, the photoresist film 201 is patterned by well-known exposure / development, and as shown in FIG. 2C, a resist pattern 202 having a square-shaped opening 202a with a side of 10 mm is formed at the center. It is assumed that Next, the thin film 112 is selectively removed by reactive ion etching using C ₂ F ₆ gas using the resist pattern 202 as a mask, and the support substrate 101 is formed on the thin film 112 as shown in FIG. It is assumed that an opening 112a that exposes the back surface is formed. Note that the resist pattern may be formed not only by photolithography using ultraviolet rays but also by lithography using electron beams.

  Next, after removing the resist pattern 202 by ashing, the supporting substrate 101 is selectively removed using the thin film 112 as a mask by wet etching using an alkali such as a potassium hydroxide (KOH) aqueous solution. As shown in (e), an opening 101 a is formed in the center of the support substrate 101. The opening 101a is formed so as to penetrate the support substrate 101. In this wet etching, since the (111) plane of the single crystal silicon is hardly etched, the etching hardly proceeds in the plane direction of the support substrate 101, and the side surface having an angle of about 54 ° with respect to the plane of the support substrate 101 is formed. The opening 101a is formed in the provided state.

  In the above description, single crystal silicon having a main surface of (100) as the support substrate 101 is used. However, the present invention is not limited to this. For example, single crystal silicon whose main surface is the (110) plane may be used. In this case, the opening can be formed with a side surface substantially perpendicular to the plane of the support substrate 101 by wet etching with an aqueous potassium hydroxide solution.

  Next, on the thin film 102 formed on the main surface side of the support substrate 101, as shown in FIG. 3F, a lower antioxidant layer 103 made of silicon carbide and having a thickness of about 2 nm is formed. A filter layer 104 made of aluminum and having a thickness of about 100 nm is formed, and an upper antioxidant layer 105 made of silicon carbide and having a thickness of about 2 nm is formed thereon. The lower antioxidant layer 103 and the upper antioxidant layer 105 may be formed, for example, by depositing silicon carbide by magnetron sputtering. The filter layer 104 may also be formed by depositing aluminum by magnetron sputtering. The thin film 102 installed in the opening 101a of the substrate 101 formed in a frame shape is, for example, stretched over the opening 101a to function as a membrane, and is also described above on the thin film 102 in the region of the opening 101a. Each layer can be formed.

Next, the thin film 102 is selectively removed from the back side of the support substrate 101 by reactive ion etching using C ₂ F ₆ gas using the support substrate 101 as a mask. Since silicon nitride is used for the thin film 102, the thin film 102 can be etched with a selection ratio with respect to the lower antioxidant layer 103 made of silicon carbide, and the lower antioxidant layer 103 is damaged. In other words, the filter layer 104 is not exposed. By this selective etching, an opening 102a is formed in the thin film 102 as shown in FIG. Note that the thin film 112 is also removed by forming the opening 102a. By forming the opening 102 a, a part of the lower antioxidant layer 103 is exposed on the back side of the support substrate 101. Even in this state, the lower antioxidant layer 103, the filter layer 104, and the upper antioxidant layer 105 are laid over the opening 102 a of the thin film 102. By the above, the soft X-ray filter in Example 1 is obtained.

  The soft X-ray filter of Example 1 described above functions as a filter that transmits soft X-rays having a wavelength of 25 to 40 nm from broadband radiation generated from synchrotron radiation, and has transmission characteristics as indicated by a solid line in FIG. Is obtained. In the production described above, the lower antioxidant layer 103 and the upper antioxidant layer 105 are not formed, and the transmittance is more than doubled at a wavelength of 25 to 40 nm compared to a soft X-ray filter (dotted line) manufactured under the same conditions. Is obtained.

[Example 2]
Next, Example 2 will be described. In the soft X-ray filter of Example 2, the thin film 102 is made of silicon nitride, the lower antioxidant layer 103 and the upper antioxidant layer 105 are made of magnesium fluoride (MgF ₂ ), and the filter layer 104 is tin (Sn). ).

  Hereinafter, a method for manufacturing the soft X-ray filter of the second embodiment will be described. In the following description, the process diagrams of FIGS. 2A to 2E, 3F, and 3G are also used. First, a support substrate 101 made of single crystal silicon having a main surface of (100) is prepared, and silicon nitride is deposited on the main surface and back surface of the support substrate 101 by a well-known CVD method. As a result, as shown in FIG. 2A, the thin film 102 and the thin film 112 having a thickness of about 200 nm are formed on the main surface and the back surface of the support substrate 101.

Next, as shown in FIG. 2B, a positive type photoresist film 201 that is sensitive to ultraviolet rays is formed on the thin film 112 on the back surface side. Next, the photoresist film 201 is patterned by well-known exposure / development, and as shown in FIG. 2C, a resist pattern 202 having a square-shaped opening 202a with a side of 10 mm is formed at the center. It is assumed that Next, the thin film 112 is selectively removed by reactive ion etching using C ₂ F ₆ gas using the resist pattern 202 as a mask, and the support substrate 101 is formed on the thin film 112 as shown in FIG. It is assumed that an opening 112a that exposes the back surface is formed.

  Next, after removing the resist pattern 202 by ashing, the supporting substrate 101 is selectively removed using the thin film 112 as a mask by wet etching using an aqueous potassium hydroxide (KOH) solution, and FIG. As shown in FIG. 4, an opening 101a is formed at the center of the support substrate 101. The above is the same as that of the first embodiment.

  Next, on the thin film 102 formed on the main surface side of the support substrate 101, as shown in FIG. 3F, a lower antioxidant layer 103 made of magnesium fluoride and having a thickness of about 2 nm is formed. Then, a filter layer 104 made of tin with a thickness of about 50 nm is formed, and an upper antioxidant layer 105 made of magnesium fluoride with a thickness of about 2 nm is formed thereon. The lower antioxidant layer 103 and the upper antioxidant layer 105 may be formed by depositing magnesium fluoride by a magnetron sputtering method, for example. The filter layer 104 may also be formed by depositing tin by magnetron sputtering. The thin film 102 laid over the opening 101a of the substrate 101 formed in a frame shape is stretched over the opening 101a and functions as a membrane. The above-described layers are also formed on the thin film 102 in the region of the opening 101a. It can be formed.

Next, the thin film 102 is selectively removed from the back side of the support substrate 101 by reactive ion etching using C ₂ F ₆ gas using the support substrate 101 as a mask. Since silicon nitride is used for the thin film 102, the thin film 102 can be etched with a selection ratio with respect to the lower antioxidant layer 103 made of magnesium fluoride, and the lower antioxidant layer 103 is damaged. The filter layer 104 is not exposed. By this selective etching, an opening 102a is formed in the thin film 102 as shown in FIG. Note that the thin film 112 is also removed by forming the opening 102a. By forming the opening 102 a, a part of the lower antioxidant layer 103 is exposed on the back side of the support substrate 101. The soft X-ray filter in Example 2 is obtained by the above.

[Example 3]
Next, Example 3 will be described. In the soft X-ray filter of Example 3, the thin film 102 is made of diamond-like carbon, the lower antioxidant layer 103 and the upper antioxidant layer 105 are made of zirconium nitride (ZrN), and the filter layer 104 is zirconium (Zr). It consists of The lower antioxidant layer 103 and the upper antioxidant layer 105 are metal nitrides constituting the filter layer 104. Note that diamond-like carbon (diamond-like carbon) is an amorphous substance in which, for example, the ratio of sp ³ bonds of carbon, which is a bond type of diamond, is as high as 80% or more.

  Hereinafter, a method for manufacturing the soft X-ray filter of the third embodiment will be described. In the following description, the process diagrams of FIGS. 2A to 2E, 3F, and 3G are also used. First, a support substrate 101 made of single crystal silicon having a main surface of (100) is prepared, and diamond-like carbon is deposited on the main surface and the back surface of the support substrate 101 by a well-known CVD method. As a result, as shown in FIG. 2A, the thin film 102 and the thin film 112 having a thickness of about 200 nm are formed on the main surface and the back surface of the support substrate 101.

Next, as shown in FIG. 2B, a positive type photoresist film 201 that is sensitive to ultraviolet rays is formed on the thin film 112 on the back surface side. Next, the photoresist film 201 is patterned by well-known exposure / development, and as shown in FIG. 2C, a resist pattern 202 having a square-shaped opening 202a with a side of 10 mm is formed at the center. It is assumed that Next, the thin film 112 is selectively removed by reactive ion etching using oxygen (O ₂ ) gas using the resist pattern 202 as a mask, and the support substrate 101 is formed on the thin film 112 as shown in FIG. It is assumed that an opening 112a that exposes the back surface of the substrate is formed.

  Next, after removing the resist pattern 202 by ashing, the supporting substrate 101 is selectively removed using the thin film 112 as a mask by wet etching using an aqueous potassium hydroxide (KOH) solution, and FIG. As shown in FIG. 4, an opening 101a is formed at the center of the support substrate 101.

  Next, on the thin film 102 formed on the main surface side of the support substrate 101, as shown in FIG. 3F, a lower antioxidant layer 103 made of zirconium nitride and having a thickness of about 2 nm is formed. A filter layer 104 made of zirconium and having a thickness of about 50 nm is formed, and an upper antioxidant layer 105 made of zirconium nitride and having a thickness of about 2 nm is formed thereon. The lower antioxidant layer 103 and the upper antioxidant layer 105 may be formed, for example, by depositing zirconium nitride by magnetron sputtering. The filter layer 104 may also be formed by depositing zirconium by magnetron sputtering. The thin film 102 is stretched over the opening 101a of the substrate 101 to function as a membrane, and the above-described layers can be formed also on the thin film 102 in the region of the opening 101a.

  Next, the thin film 102 is selectively removed from the back surface side of the support substrate 101 by reactive ion etching using oxygen gas using the support substrate 101 as a mask. Since diamond-like carbon is used for the thin film 102, the thin film 102 can be etched with a selection ratio with respect to the lower antioxidant layer 103 made of zirconium nitride, and the lower antioxidant layer 103 is damaged. The filter layer 104 is not exposed. By this selective etching, an opening 102a is formed in the thin film 102 as shown in FIG. Note that the thin film 112 is also removed by forming the opening 102a. By forming the opening 102 a, a part of the lower antioxidant layer 103 is exposed on the back side of the support substrate 101. By the above, the soft X-ray filter in Example 3 is obtained.

[Example 4]
Next, Example 4 will be described. In the soft X-ray filter of Example 4, the thin film 102 is made of silicon carbide, the lower antioxidant layer 103 and the upper antioxidant layer 105 are made of ruthenium (Ru), and the filter layer 104 is made of titanium (Ti). It is what.

  Hereinafter, a method for manufacturing the soft X-ray filter of the fourth embodiment will be described. In the following description, the process diagrams of FIGS. 2A to 2E, 3F, and 3G are also used. First, a support substrate 101 made of single crystal silicon having a main surface of (100) is prepared, and silicon carbide is deposited on the main surface and back surface of the support substrate 101 by a well-known CVD method. As a result, as shown in FIG. 2A, the thin film 102 and the thin film 112 having a thickness of about 200 nm are formed on the main surface and the back surface of the support substrate 101.

Next, as shown in FIG. 2B, a positive type photoresist film 201 that is sensitive to ultraviolet rays is formed on the thin film 112 on the back surface side. Next, the photoresist film 201 is patterned by well-known exposure / development, and as shown in FIG. 2C, a resist pattern 202 having a square-shaped opening 202a with a side of 10 mm is formed at the center. It is assumed that Next, the thin film 112 is selectively removed by reactive ion etching using CF ₄ gas using the resist pattern 202 as a mask, and the back surface of the support substrate 101 is formed on the thin film 112 as shown in FIG. It is assumed that the exposed opening 112a is formed.

Next, after removing the resist pattern 202 by ashing, the supporting substrate 101 is selectively removed using the thin film 112 as a mask by wet etching using an aqueous potassium hydroxide (KOH) solution, and FIG. As shown in FIG. 4, an opening 101a is formed at the center of the support substrate 101. The above is the same as Example 1 described above except that silicon carbide is used for the thin film and CF ₄ is used instead of C ₂ F ₆ .

  Next, on the thin film 102 formed on the main surface side of the support substrate 101, as shown in FIG. 3F, a lower antioxidant layer 103 made of ruthenium and having a thickness of about 2 nm is formed. The filter layer 104 having a thickness of about 100 nm is formed, and the upper antioxidant layer 105 having a thickness of about 2 nm made of ruthenium is formed thereon. The lower antioxidant layer 103 and the upper antioxidant layer 105 may be formed by depositing ruthenium by a magnetron sputtering method, for example. The filter layer 104 may also be formed by depositing titanium by magnetron sputtering. The thin film 102 is stretched over the opening 101a of the substrate 101 to function as a membrane, and the above-described layers can be formed also on the thin film 102 in the region of the opening 101a.

Next, the thin film 102 is selectively removed from the back surface side of the support substrate 101 by reactive ion etching using CF ₄ gas using the support substrate 101 as a mask. Since silicon carbide is used for the thin film 102, the thin film 102 can be etched with a selection ratio with respect to the lower antioxidant layer 103 made of ruthenium, and the lower antioxidant layer 103 is damaged. Therefore, the filter layer 104 is not exposed. By this selective etching, an opening 102a is formed in the thin film 102 as shown in FIG. Note that the thin film 112 is also removed by forming the opening 102a. By forming the opening 102 a, a part of the lower antioxidant layer 103 is exposed on the back side of the support substrate 101. By the above, the soft X-ray filter in Example 4 is obtained.

  In the above description, the opening 102a is formed to have the same size as the opening 101a of the support substrate 101. However, the present invention is not limited to this. For example, as shown in FIG. 5, an opening 502 a narrower than the opening 101 a may be formed in the thin film 102. In the above description, the lower antioxidant layer 103, the filter layer 104, and the upper antioxidant layer 105 are formed over the entire area of the support substrate 101 and the thin film 102. However, the present invention is not limited to this. For example, as shown in FIG. 6, a lower antioxidant layer 103, a filter layer 104, and an upper antioxidant layer 105 may be formed on a part of the thin film 102 so as to be wider than the opening 102a. Further, as shown in FIG. 7, the lower antioxidant layer 103, the filter layer 104, and the upper antioxidant layer 105 may be formed on a part of the thin film 102 so as to be wider than the opening 502a.

  In the above description, aluminum, tin, zirconium, and titanium have been described as examples of materials used for the filter layer. However, the material is not limited to this, but magnesium (Mg), germanium (Ge), tantalum (Ta), rhenium (Re), scandium (Sc), chromium (Cr), and yttrium (Y) can be used.

In the above description, when aluminum is used for the filter layer, the antioxidant layer made of silicon carbide is formed. However, the present invention is not limited to this, and an antioxidant layer made of magnesium fluoride or an antioxidant layer made of carbon is used. You may do it. In the above description, when zirconium is used for the filter layer, the antioxidant layer made of zirconium nitride is formed. However, the present invention is not limited to this, and the antioxidant layer made of ruthenium and the antioxidant layer made of boron nitride (BN). Alternatively, an antioxidant layer made of boron carbide (B ₄ C) may be used.

  Further, in the above, when titanium is used for the filter layer, the antioxidant layer made of ruthenium is formed. However, the present invention is not limited to this, and the antioxidant layer made of titanium nitride which is the nitride of the filter layer is made of boron nitride. An antioxidant layer made of boron, an antioxidant layer made of boron carbide, an antioxidant layer made of gold (Au), or an antioxidant layer made of platinum (Pt) may be used. With these combinations, desired soft X-ray transmission characteristics can be obtained.

  When tantalum is used for the filter layer, an antioxidant layer made of titanium nitride, an antioxidant layer made of boron nitride, an antioxidant layer made of boron carbide, an antioxidant layer made of gold, or an antioxidant layer made of platinum. What is necessary is just to combine. When rhenium is used for the filter layer, an antioxidant layer made of zirconium nitride, an antioxidant layer made of ruthenium, an antioxidant layer made of boron nitride, or an antioxidant layer made of boron carbide may be combined. Moreover, when using magnesium for a filter layer, what is necessary is just to combine the antioxidant layer which consists of magnesium fluoride which is a fluoride of a filter layer. Further, when germanium is used for the filter layer, an antioxidant layer made of silicon may be combined.

  Further, when scandium is used for the filter layer, an antioxidant layer made of magnesium fluoride may be combined. When chromium is used for the filter layer, a combination of an antioxidant layer made of gold, an antioxidant layer made of platinum, an antioxidant layer made of boron nitride, an antioxidant layer made of boron carbide, and an antioxidant layer made of carbon is combined. Just do it. When yttrium is used for the filter layer, an antioxidant layer made of ruthenium, an antioxidant layer made of boron nitride, and an antioxidant layer made of boron carbide may be combined. With these combinations, desired soft X-ray transmission characteristics can be obtained.

  Note that metal nitrides, carbides, and fluorides used for the filter layer can be used for the antioxidant layer. By doing so, for example, in the formation of a film by sputtering, the gas introduced simultaneously By changing the composition, a continuous film can be easily formed, which is better from the viewpoint of preventing oxidation of the filter layer in the manufacturing process. Further, a stronger adhesive force can be obtained between the filter layer and the antioxidant layer. Further, desired soft X-ray transmission characteristics can be obtained more easily.

  As the thin film 102, silicon nitride, silicon carbide, diamond, and diamond-like carbon can be used. These materials are not limited to the CVD method, and can be formed by a CVD method using ECR plasma as an assist. For the thin film 102, a material that can be etched with a selection ratio with respect to the lower antioxidant layer 103 may be used. In the above-described embodiment, it is necessary to apply a material that can be etched with a selection ratio to the thin film 102 even for silicon used as the support substrate 101. However, when the thin film 102 is used as a support structure, the support substrate 101 is not necessarily required, and the thin film 102 does not need to be made of a material having a selection ratio with respect to silicon.

  Further, it is possible to form a support structure only with a support substrate made of a predetermined material without using the thin film 102 as the support thin film. A laminated structure (film) composed of the lower antioxidant layer 103, the filter layer 104, and the upper antioxidant layer 105 may be formed on a support structure having an opening.

[Example 5]
Next, the case where the supporting thin film is not used will be described together with the manufacturing method.

  First, as shown in FIG. 8A, a lower antioxidant layer 103 made of ruthenium and having a thickness of about 3 nm is formed on a substrate 801 made of sodium chloride (NaCl) crystal, and is made of zirconium. A filter layer 104 with a thickness of about 200 nm is formed, and an upper antioxidant layer 105 with a thickness of about 3 nm made of ruthenium is formed thereon. The lower antioxidant layer 103 and the upper antioxidant layer 105 may be formed by depositing ruthenium by a magnetron sputtering method, for example. The filter layer 104 may also be formed by depositing zirconium by magnetron sputtering.

  Next, as shown in FIG. 8B, a predetermined container 803 containing water 802 is prepared, and a laminated film composed of the lower layer antioxidant layer 103, the filter layer 104, and the upper layer antioxidant layer 105 together with the substrate 801. Is immersed in water 802. As a result, the water-soluble substrate 801 is dissolved in water and removed from the laminated film, and as shown in FIG. 8C, the lower antioxidant layer 103 and the upper antioxidant layer 105 are formed on the front and back surfaces. The formed filter layer 104 is suspended in the water 802.

  Next, as shown in FIG. 8D, an opening having an opening size of about 5 mm is formed in water 802 in which a laminated film composed of the lower antioxidant layer 103, the filter layer 104, and the upper antioxidant layer 105 is floating. A metallic frame (support structure) 804 having a portion is inserted. In this way, the laminated film is scooped up by the frame 804 that has entered the water 802. As shown in FIG. 8E, the lower antioxidant layer 103, the filter layer 104, and the upper layer are formed in the opening of the frame 804. It is assumed that a laminated film composed of the antioxidant layer 105 is installed.

  As a result, the filter layer 104 is formed on the frame 804 serving as the support structure, and the lower antioxidant layer 103 is formed in contact with the lower surface of the filter layer 104 on the frame 804 side, and in contact with the upper surface of the filter layer 104. Thus, a soft X-ray filter in which the upper antioxidant layer 105 is formed is obtained. Here, FIG. 8E shows a state in which the lower antioxidant layer 103 is disposed on the frame 804, the filter layer 104 is disposed thereon, and the upper antioxidant layer 105 is disposed thereon. However, the present invention is not limited to this, and the upper antioxidant layer 105 may be disposed on the frame 804 side.

  Instead of the frame 804, a metallic mesh having a plurality of openings of about 0.5 mm may be used as the support structure. Further, the frame 804 is not limited to metal, and may be made of a material that does not dissolve in water, such as plastic. According to the manufacturing method described above, since the antioxidant layer only needs to be made of a material that does not dissolve in water, the degree of freedom in combining the filter layer and the antioxidant layer can be increased. Note that the substrate 801 is not limited to sodium chloride, and may be formed of a water-soluble salt such as potassium chloride, sodium bromide, or potassium bromide.

  According to the present invention described above, the decrease in strength and the decrease in transmittance due to the oxidation of the filter layer, which could not be achieved in the past, are solved. Needless to say, the present invention is not limited to the configuration of the above-described embodiment, and can be appropriately changed within the scope of the technical idea of the present invention.

It is sectional drawing which shows schematically the structure of the soft X-ray filter in embodiment of this invention. It is process drawing for demonstrating the manufacturing method of the soft X-ray filter in embodiment of this invention. It is process drawing for demonstrating the manufacturing method of the soft X-ray filter in embodiment of this invention. FIG. 6 is a characteristic diagram showing transmission characteristics at a wavelength of 25 to 40 nm in the soft X-ray filter of Example 1. It is sectional drawing which shows roughly the structure of the other soft X-ray filter in embodiment of this invention. It is sectional drawing which shows roughly the structure of the other soft X-ray filter in embodiment of this invention. It is sectional drawing which shows roughly the structure of the other soft X-ray filter in embodiment of this invention. It is process drawing for demonstrating the manufacturing method of the other soft X-ray filter in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Support substrate, 101a ... Opening part, 102 ... Thin film (supporting thin film), 102a ... Opening part, 103 ... Lower layer antioxidant layer, 104 ... Filter layer, 105 ... Upper layer antioxidant layer, 112 ... Thin film, 112a ... Opening part , 201... Photoresist film, 202... Resist pattern, 202 a.

Claims (7)

A filter layer made of a metal thin film that transmits soft X-rays formed on a support structure having an opening;
A lower antioxidant layer formed in contact with the lower surface of the filter layer on the support structure side;
A soft X-ray filter comprising at least an upper antioxidant layer formed in contact with the upper surface of the filter layer. The soft X-ray filter according to claim 1,
The soft X-ray filter, wherein the metal is selected from aluminum, zirconium, tin, magnesium, titanium, germanium, tantalum, rhenium, scandium, chromium, and yttrium. The soft X-ray filter according to claim 2,
The lower antioxidant layer and the upper antioxidant layer are selected from silicon, carbon, boron, and nitrides, carbides, fluorides thereof, and gold, platinum, and ruthenium. Soft X-ray filter. The soft X-ray filter according to claim 1 or 2,
The soft X-ray filter, wherein the lower antioxidant layer and the upper antioxidant layer are selected from the metal nitride, carbide, and fluoride. In the soft X-ray filter according to any one of claims 1 to 4,
The support structure is
A support substrate with an opening;
A soft X-ray filter comprising: a support thin film formed on the support substrate and having an opening. A first step in which a support thin film is formed on the main surface of the support substrate;
A second step in which an opening penetrating the support substrate is formed from the back surface of the support substrate;
A third step in which a lower antioxidant layer is formed on the support thin film;
A fourth step in which a filter layer made of a metal thin film that transmits soft X-rays is formed in contact with the lower antioxidant layer;
A fifth step in which an upper antioxidant layer is formed in contact with the filter layer;
A soft X-ray filter comprising: a sixth step of selectively removing the support thin film to form an opening through which the lower antioxidant layer is exposed through the support thin film Manufacturing method. A first step in which a lower antioxidant layer is formed on a substrate composed of a water-soluble salt;
A second step in which a filter layer made of a metal thin film that transmits soft X-rays is formed in contact with the lower antioxidant layer;
A third step in which an upper antioxidant layer is formed in contact with the filter layer;
The substrate on which the laminated film composed of the lower antioxidant layer, the filter layer, and the upper antioxidant layer is formed is immersed in water to dissolve the substrate in the water, and the laminated film is in the water. A fourth step of floating;
A support structure having an opening in the water is infiltrated, and the laminated film floating in the water is scooped up by the support structure, so that the stacked structure is formed in the opening of the support structure. A soft X-ray filter manufacturing method comprising: at least a fifth step in which a film is installed.

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