JP5341416B2 - X-ray condenser lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high intensity X-ray microbeams at nanometer levels. <P>SOLUTION: An X-ray condensing lens has a structure of a guided wave route where the upside and bottom of a carbon layer 3 with a refractive index at N<SB>1</SB>are squeezed by ruthenium layers 2 and 4 with a refractive index at N<SB>2</SB>, and includes an X-ray phase shifter layer 5 with a refractive index at N<SB>3</SB>formed in a part of the carbon layer 3 and an X-lay shielding layer 6 with a refractive index at N<SB>2</SB>or higher which is formed in a part on the surface of the upper ruthenium layer 4. The phase shifter layer 5 is placed in a domain between the position of Y<SB>n</SB>(Q/P) and the position Y<SB>n</SB>((Q-1)/P) when the wavelength of X rays, the focal length and the distance along the AY direction from the center of an X-ray beam are taken as &lambda;, f and Y<SB>n</SB>(Q/P)=än&lambda;f+2&lambda;f(Q/P-1)}<SP>1/2</SP>(n is an even number and P and Q are integral numbers satisfying 1&le;Q&le;P) , respectively, and the length t(Q/P) of the X-ray phase shifter layer 5 is t(Q/P)=(Q-1)&times;&lambda;/äP&times;(N<SB>3</SB>-N<SB>1</SB>)}. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an X-ray condensing device, and more particularly to an X-ray condensing lens that condenses light using a waveguide, a phase shift zone, and an X-ray shielding structure in combination.

  In recent years, with the progress of nanotechnology development, structural evaluation of materials at the nanometer level is required. There are scanning microscopes, electron microscopes and the like as nanometer level evaluation methods, but all of them require high vacuum conditions and thinning of the sample, and it is difficult to measure the sample to be observed as it is. On the other hand, with the progress of X-ray focusing technology in recent years, micrometer level X-ray beams have been obtained, and X-ray diffraction and fluorescent X-rays using such X-ray beams have been obtained. Material evaluation such as analysis has finally become possible.

  X-ray beam condensing can be broadly divided into (A) a method using an X-ray optical element such as an X-ray mirror (see Non-Patent Document 1), and (B) asymmetric Bragg reflection of a crystal. (C) a method using an X-ray Fresnel zone plate (see Non-Patent Document 3 and Non-Patent Document 4), and (D) a method using a transmissive laminated zone plate (Non-Patent Document 2). There is a technique (see Non-Patent Document 6) that uses an X-ray waveguide.

  Of these, the method of using the optical element for X-rays such as the X-ray mirror of (A) and the method of using the asymmetric Bragg reflection of the crystal of (B) are almost at the technical limit at present. Condensation is difficult.

On the other hand, in the hard X-ray region where the X-ray energy is 5 keV or more, a condensed beam having a beam size of 100 nanometers or less is obtained by the method using the X-ray Fresnel zone plate of (C). When the Fresnel zone plate is irradiated with an X-ray beam, a part of the X-ray beam is absorbed by the zone plate and is not transmitted, but the other X-ray beams pass through the zone plate as they are. At this time, assuming that the wavelength of the X-ray beam is λ and the focal length of the X-ray Fresnel zone plate is f, (2nλf) ^1/2 (n = 0), 1, 2,... And the position of {(2n + 1) λf} ^1/2 , or the position of {(2n + 1) λf} ^1/2 and {(2n + 2) λf} ^{1 / If} a shielding zone made of a material that does not transmit X-rays is provided between the position ² and the transmitted X-rays interfere with each other, the X-ray beam can be condensed.

  This condensing principle is the same as that of visible light, and details thereof are described in Non-Patent Document 7, for example, and it is known that the spatial resolution of the zone plate condensing system is substantially equal to the outermost zone width. . Therefore, in the case of an X-ray Fresnel zone plate, the maximum spatial resolution is defined by the width of the narrowest shielded zone constituting the zone plate. In order to manufacture such a zone plate, lithography technology for semiconductor manufacturing including electron beam drawing is used. Although the semiconductor lithography technology itself can draw a linear pattern of 10 nanometers, when producing a ring-shaped pattern necessary as an X-ray Fresnel zone plate, drawing of a width of about 40 nanometers is currently limited. Yes, the resolution of the X-ray Fresnel zone plate itself is about 50 nanometers. Furthermore, when producing an X-ray Fresnel zone plate, since it is necessary to precisely produce a large number of ring-shaped patterns, the X-ray Fresnel zone plate itself is very expensive.

In the X-ray Fresnel zone plate, X-rays were collected by providing a shielding zone through which X-rays cannot be transmitted. Further, in order to increase the light collection efficiency, an X-ray phase shifter layer that transmits X-rays but shifts the phase of X-rays is provided instead of the shielding zone, or this phase shifter layer is formed in a multistage structure. Thus, a method for further improving the light collection efficiency has been proposed. On the other hand, in the case of the method using the transmissive laminated zone plate of (D), a structure in which a heavy element layer that transmits X-rays and a light element layer that transmits X-rays is used. In Non-Patent Document 5, the distance along the Z direction from the center of the X-ray beam is a position of (2nλf ₁ ) ^1/2 (n = 0, 1, 2,...) And {(2n + 1) λf ₁ }. X-rays are linearly collected by the laminated Fresnel zone plate structure disposed in either the first region between the ^half positions or the second region excluding the first region. Possibilities have been proposed. In addition, a method of condensing dots in a spot shape by combining two stacked Fresnel zone plate structures has been recently proposed.

On the other hand, in the case of the method using the X-ray waveguide of (E), the size of the X-ray beam is determined by the size of the core constituting the waveguide. Here, when the refractive index in the X-ray region of the core layer is N ₁ and the refractive index in the X-ray region of the cladding layer covering the core layer is N ₂ , (the real part of N ₁ ) <(the real number of N ₂ ) Part). When an X-ray beam is incident on the core layer of the X-ray waveguide, the X-ray beam travels through the core layer. At this time, when the thickness D of the core layer is sufficiently small, only X-rays in a specific state are transmitted. At this time, the thickness D of the core layer, the wavelength λ of the X-ray beam, and the cladding layer of the X-ray beam Is known to have the following relationship with the incident angle φ (see Non-Patent Document 8).
2Dsin (φ) = mλ (m = 0, 1, 2,...) (1)

  The condition of formula (1) indicates that there is a limit to the incident angle φ of the X-ray incident on the X-ray waveguide, and X-rays having other incident angles cannot pass through the core layer. Is shown. The angle at which total reflection occurs is selected as the incident angle φ of the X-ray beam from the core layer to the cladding layer, and the length is such that all the X-ray beam passing through the cladding layer is absorbed and does not pass through the waveguide exit. When the X-ray waveguide is used, the X-ray beam can be condensed to the size of the core layer at the exit of the waveguide. Since such an X-ray waveguide can be manufactured by vapor deposition, it is easy to reduce the thickness of the core layer to 10 nanometers or less, and an X-ray beam having a size of several nanometers can be manufactured. It is possible in principle.

  However, in the case of a method using an X-ray waveguide, an X-ray beam can be condensed in the thickness direction of the core, but the in-plane direction of the core perpendicular to the thickness direction and the traveling direction of the beam. X-rays cannot be collected. That is, the X-rays that can be extracted at the exit of the X-ray waveguide have the same size as the incident X-rays in the horizontal direction. It is difficult to obtain a point-shaped X-ray microbeam that is focused in a two-dimensional direction.

  As described above, it is difficult to obtain an X-ray beam having a size of 10 nanometers by a method using an X-ray Fresnel zone plate, and an X-ray beam having a size of several nanometers by a method using an X-ray waveguide. Although it is possible to obtain a ray beam, there is a problem that the X-ray beam is condensed in only a one-dimensional direction, an X-ray beam condensed in a two-dimensional direction cannot be obtained, and the X-ray intensity is weak. There was a point (refer nonpatent literature 9). As described above, with the progress of research on nanostructured materials, a technique for evaluating nanostructured materials with a spatial resolution of 10 nanometer level is required. However, the conventional X-ray beam focusing method has a level of 10 nanometer level. It is difficult to achieve a spatial resolution of

In order to overcome such technical difficulties, the inventor sandwiched the upper and lower sides of the core layer having a refractive index N ₁ in the X-ray region with a clad layer having a refractive index N ₂ , so that the refractive indexes N ₁ and N ₁ Fresnel zone formed by a shielding layer that does not transmit X-rays in part of the waveguide, using an X-ray waveguide having a relationship of (real part of N ₁ ) <(real part of N ₂ ) between ₂ An X-ray condensing lens that can form an X-ray microbeam condensed at a nanometer level in the vertical direction and the horizontal direction by incorporating a plate has been proposed (see Patent Document 1). Hereinafter, the X-ray condenser lens proposed in Patent Document 1 is referred to as the X-ray condenser lens of Conventional Technique 1.

FIG. 5A is a plan view showing the configuration of the X-ray condenser lens of Prior Art 1, and FIG. 5B is a cross-sectional view taken along the line I-I of the X-ray condenser lens of FIG. In FIG. 5A, it is assumed that an X-ray shielding layer and an X-ray beam under the upper ruthenium layer described later are seen through.
The X-ray condenser lens includes an X-ray waveguide portion 114 for condensing the X-ray beam in the vertical direction, an X-ray zone plate portion 115 for condensing the X-ray beam in the horizontal direction, and an X-ray collector. And an optical part 116.

  5A and 5B, reference numeral 108 denotes a silicon substrate, 109 denotes a lower ruthenium layer which is a cladding layer formed on the silicon substrate 108, and 110 denotes a core formed on the lower ruthenium layer 109. A carbon layer 111, an upper ruthenium layer 111 being a cladding layer formed on the carbon layer 110, and a part 112 of an X-ray waveguide composed of the lower ruthenium layer 109, the carbon layer 110, and the upper ruthenium layer 111. 2 is an X-ray shielding layer made of a tantalum material that functions as an X-ray zone plate.

The X-ray shielding layer 112 has a distance along the direction orthogonal to the traveling direction of the X-ray beam 113 from the center of the X-ray beam 113 when the wavelength of the X-ray is λ and the focal length of the condenser lens is f. Any one of the first region between the position of Z _2n (n is 0, 1, 2,...) And the position of Z _{2n + 1} and the second region excluding the first region. And disposed upstream from the X-ray waveguide outlet 17 by a focal length f along the direction opposite to the traveling direction of the X-ray beam 113. 5A and 5B, the traveling direction of the X-ray beam 113 is the right direction in FIGS. 5A and 5B and the direction orthogonal to the traveling direction of the X-ray beam 113. It is the up-down direction of FIG.

The distances (coordinates) Z _2n and Z _{2n + 1} from the center of the X-ray beam of the X-ray shielding layer 112 are obtained by the following equations.
Z _2n = (2nλf) ^1/2 (2)
Z _{2n + 1} = {(2n + 1) λf} ^1/2 (3)

  Further, the inventor replaces the X-ray shielding layer 112 in the X-ray condenser lens of the prior art 1 with an X-ray phase shifter layer that transmits X-rays but shifts the phase of X-rays, thereby transmitting X-rays. The X-ray condensing lens which can make a rate 4 times was proposed (Japanese Patent Application No. 2007-210831). Hereinafter, the X-ray condensing lens proposed in Japanese Patent Application No. 2007-210831 will be referred to as the X-ray condensing lens of Prior Art 2. Furthermore, the inventor can further improve the X-ray transmittance by replacing the X-ray phase shifter layer in the X-ray condenser lens of the prior art 2 with a phase shifter layer having a multi-stage structure. (Japanese Patent Application No. 2007-295244). Hereinafter, the X-ray condensing lens proposed in Japanese Patent Application No. 2007-295244 will be referred to as the X-ray condensing lens of Prior Art 3.

JP 2008-2939 A Yamauchi et al., “Two-dimensional Submicron Focusing of Hard X-rays by Two Elliptical Mirrors Fabricated by Plasma Chemical Vaporization Machining and Elastic Emission Machining”, Jpn.J.Appl.Phys., Vol.42, 2003, p.7129-7134 Tsusaka et al., “Formation of Parallel X-Ray Microbeam and Its Application”, Japanese Journal of Applied Physics, Vol.39, 2000, p.635-637 E. Spiller, “Soft X-ray Optics”, The international Society for Optical Engineering, p. 81-97 E. DiFabrizio, et al., “High-efficiency multilevel zone plates for keV X-rays”, Nature, Vol. 401, 1999, p. 895-898 HCKang, J.Maser, GBStephenson, C.Liu, R.Conley, ATMacrander, and S.Vogt, “Nanometer Linear Focusing of Hard X Rays by a Multilayer Laue Lens”, Phys. Rev. Lett., 96, 127401, 2006 Jun Kawai, “X-ray traveling wave”, Surface Science, Vol. 22, no. 6, p. 397-403, 2001 Hiroshi Kubota, "Wave Optics", Iwanami Shoten, p. 305, 1971 W. Jark et al., “High gain beam compression in new-generation thin-film x-ray waveguide”, Applied Physics Letters, Vol. 78, No. 9, 2001, p.1192-1194 Sadao Aoki et al., “Basics of Synchrotron Radiation Experiment III. X-ray Microbeam and its Applications”, PF Roundtable, p. 68-86, 1997

  In the conventional X-ray condenser lenses of 1, 2, and 3, it is assumed that incident X-rays are introduced into the core layer of the X-ray waveguide from the side surface of the X-ray waveguide. In these conventional techniques, except for X-rays introduced into the nanoscale core layer, X-rays are almost absorbed by the cladding structure, and the efficiency of introducing X-rays into the X-ray waveguide is very poor. In order to solve this problem, a method has been proposed in which another condensing lens such as an X-ray mirror is provided further upstream of the X-ray condensing lens and X-rays are introduced into the core layer of the X-ray waveguide. However, in this case, the entire condenser lens is expensive, and complicated adjustment of the optical system is required. Furthermore, even if this method is used, it is very difficult to introduce incident X-rays collected by an X-ray mirror or the like only into the nanoscale core layer at the entrance of the waveguide. Since X-rays are incident, X-rays are greatly lost as a result.

  On the other hand, if a method called resonance beam coupling is used, X-rays can be incident on the core layer from the surface of the upper cladding layer, so that X-rays can be effectively introduced into the waveguide (non-patented). Reference 8). In this case, the thinner the upper clad layer, the more efficiently X-rays can be introduced into the core layer. However, when the core layer becomes thinner, another problem arises. That is, in the X-ray condenser lenses of the conventional techniques 1, 2, and 3, when the thickness of the upper cladding layer is thin, X-rays leak significantly from the upper cladding layer mainly while the X-ray travels through the core layer. End up. In other words, the efficiency of resonance coupling and the leakage of X-rays in the waveguide are in a reciprocal relationship.

  On the other hand, when the resonant beam coupling method is used, a part of the incident X-rays travels from the surface of the cladding layer into the waveguide, but the remaining part is totally reflected by the surface of the cladding layer above the core layer. And proceed in substantially the same direction as the X-rays collected by the X-ray condenser lens. For this reason, at the condensing point by the X-ray condenser lens, the background intensity increases due to the total reflection X-ray and its scattering, and the intensity of the condensed beam by the X-ray condenser lens becomes relatively weak. There is a problem that it ends up.

  The present invention is to solve the above-described problems, and to achieve a high-efficiency high-intensity X-ray microbeam at the nanometer level, which has been difficult with the conventional X-ray beam focusing technology. An object of the present invention is to provide an X-ray condensing lens capable of performing

The present invention provides an X-ray condenser lens that collects X-rays using an X-ray waveguide in which an X-ray refractive index of N ₁ is sandwiched between upper and lower core layers by an X-ray refractive index of N _2. And the refractive index made of a material through which X-rays pass through a part of the core layer to which X-rays enter or before the core layer is N ₃ (the real part of N ₁ <the real number of N ₃ A phase shifter layer of a portion <real part of N ₂ ) and an X-ray shielding layer having a refractive index of N ₂ or more formed on a part of the surface of the upper cladding layer formed on the core layer. The phase shifter layer has an X-ray wavelength of λ and a focal length of f, the traveling direction of the X-ray beam in the core layer is AX, and the core layer and the phase out of the directions orthogonal to the traveling direction AX The stacking direction of the cladding layer is AZ, the direction orthogonal to the AX and AZ is AY, and the AY direction from the center of the X-ray beam The distance along the _{Y n (Q / P) =} {nλf + 2λf (Q / P-1)} 1/2 when (n is the zone index even number, P and Q is an integer satisfying 1 ≦ Q ≦ P) was , Y _n (Q / P) and the position of Y _n ((Q-1) / P) (where (Q-1) / P> 0) along the AY direction disposed Te, the phase shifter layer of the AX direction length t (Q / P) is the t (Q / P) = ( Q-1) × λ / {P × (N 3 -N 1)} It is characterized by being.

Further, in one configuration example of the X-ray condenser lens of the present invention, the phase shifter layer has a position of the end face on the entrance side from the focal point of the X-ray condenser lens along the direction opposite to the traveling direction f + t (1). It is characterized by being arranged so as to be in an upstream position only.
Further, in one configuration example of the X-ray condenser lens of the present invention, the X-ray shielding layer has an incident angle of the X-ray beam to the upper cladding layer of φ, a width of the X-ray beam of W, and the upper cladding. When the film thickness of the layer is K ₁ , the film thickness of the core layer is D, and the film thickness of the lower cladding layer formed under the core layer is K ₂ , the position of the end face on the inlet side is the position of the core layer. From the end face on the outlet side to the upstream position of (f + t (1) + W / sinφ) or more along the direction opposite to the traveling direction, and from the position of the end face on the inlet side to the position of the end face on the inlet side of the core layer The X-ray shielding layer has a thickness K ₃ satisfying K ₃ > W / cos φ .

Moreover, one structural example of the X-ray condensing lens of this invention is further equipped with the laminated type Fresnel zone plate structure arrange | positioned behind the X-ray waveguide containing the said phase shifter layer, The said laminated type Fresnel zone plate structure Is a structure in which a heavy element layer made of a material that does not transmit X-rays and a light element layer made of a material that transmits X-rays are alternately stacked, and the heavy element layer is a focal point of the stacked Fresnel zone plate structure. When the distance is f ₁ , the distance along the AZ direction from the center of the X-ray beam is a position of (2mλf ₁ ) ^1/2 (m is 0, 1, 2,...) And {(2m + 1) It is characterized by being arranged in any one of the second region between the position of λf ₁ } ^1/2 and the third region excluding the second region.
Moreover, in one structural example of the X-ray condenser lens of the present invention, an end face on the exit side of the laminated Fresnel zone plate structure is along the traveling direction AX of the X-ray beam from the end face on the entrance side of the phase shifter layer. The distance L + t (1) is at the downstream side, and the relationship of f = f ₁ + L is established between the focal length f of the X-ray waveguide and the focal length f ₁ of the laminated Fresnel zone plate structure. It is characterized by .

  According to the present invention, by providing a multi-stage phase shifter layer in the X-ray waveguide, the X-ray beam can be condensed using the X-ray waveguide structure in the thickness direction of the core layer, and the thickness of the core layer is increased. With respect to the direction and the direction orthogonal to the traveling direction of the X-ray beam, the X-ray beam can be focused using the same focusing action as that of the X-ray Fresnel zone plate. As a result, in the present invention, it is possible to easily obtain a high-intensity X-ray microbeam focused to the nanometer order, such as quantum dots, nanodots, nanowires, nanoparticles, fine gates of highly integrated semiconductor materials, etc. It is possible to evaluate the structure of various nanomaterials and contribute to the development of semiconductor materials and semiconductor devices. Further, in the present invention, compared with a conventional X-ray condenser lens that uses a phase shifter layer in an X-ray waveguide structure, the condensing efficiency of the X-ray condenser lens is theoretically 1.7 when P = 3. In the case of double (68.3%) and P = 4, it can be increased to about double (81.2%), and an X-ray beam that can be easily used for analysis can be obtained. Further, in the present invention, an X-ray shielding layer is formed on a part of the surface of the upper cladding layer, and the upper cladding layer has a convex structure, thereby shielding X-rays totally reflected on the surface of the upper cladding layer. Can do. As a result, in the present invention, a coherent nanoscale X-ray focused beam with less intensity unevenness and defocusing can be obtained.

  Further, in the present invention, the phase shifter layer is arranged so that the position of the end face on the entrance side is upstream by f + t (1) along the direction opposite to the traveling direction of the X-ray beam from the focal point of the X-ray condenser lens. By doing so, it is possible to obtain an X-ray beam that can be further condensed by a normal X-ray mirror or the like and can be easily used for analysis or the like.

  Further, in the present invention, by arranging the laminated Fresnel zone plate structure behind the X-ray waveguide structure, a sufficient working distance between the X-ray condensing lens and the sample can be ensured, while at the nanometer level. It becomes possible to realize beam condensing with a diameter.

In the present invention, the end face on the exit side of the laminated Fresnel zone plate structure is set to a distance L + t (1) downstream from the end face on the entrance side of the phase shifter layer along the traveling direction AX of the X-ray beam. by such relation f = f ₁ + L is established between the focal length f ₁ of the multilayer Fresnel zone plate structure and focal length f of the X-ray waveguide, in a position away from the X-ray focusing lens It becomes easy to collect X-rays, and an X-ray beam that can be easily used for analysis can be obtained.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a plan view showing the configuration of the X-ray condenser lens according to the first embodiment of the present invention, and FIG. 1B is II of the X-ray condenser lens of FIG. It is line sectional drawing. In FIG. 1A, it is assumed that an X-ray phase shifter layer below an upper ruthenium layer, which will be described later, and an X-ray beam that passes through an X-ray condenser lens are seen through. 1A actually does not have an X-ray phase shifter layer, but FIG. 1B shows an X-ray to clarify the position of the X-ray phase shifter layer. The phase shifter layer is described for convenience.

  The X-ray condensing lens of the present embodiment incorporates a Fresnel zone plate in a part of the X-ray waveguide, condenses the X-ray beam 7 in the vertical direction, and guides the X-ray beam 7 to the X-ray guide. An X-ray waveguide portion 8 for effectively introducing into the waveguide, an X-ray waveguide portion 9 for effectively propagating X-rays, and an X-ray for condensing the X-ray beam 7 in the horizontal direction The X-ray condensing unit 11 is configured to reduce the loss of X-rays traveling through the X-ray waveguide and shield the total reflection X-rays.

  In FIG. 1, 1 is a silicon substrate, 2 is a lower ruthenium layer which is a cladding layer formed on the silicon substrate 1, 3 is a carbon layer which is a core layer formed on the lower ruthenium layer 2, and 4 is carbon. An upper ruthenium layer 5, which is a cladding layer formed on the layer 3, is an X-ray zone plate formed in a part of an X-ray waveguide composed of the lower ruthenium layer 2, the carbon layer 3 and the upper ruthenium layer 4. An X-ray phase shifter layer 6 made of a silver material functioning as an X-ray shielding layer is formed on a part of the surface of the upper ruthenium layer 4 and also functions as a cladding layer.

In the example of FIGS. 1A and 1B, the center of the X-ray beam is the II line in FIG. 1A, the traveling direction of the X-ray beam is AX, and the direction orthogonal to the traveling direction AX is the same. Among these, the stacking direction of the core layer and the cladding layer of the X-ray waveguide lens structure is AZ, and the direction orthogonal to AZ and AZ is AY. Here, the refractive index in the X-ray region of the core layer of the X-ray waveguide structure is N ₁ , the refractive index in the X-ray region of the cladding layer is N ₂ , and the refractive index of the phase shifter layer is N _3. Between the rates N ₁ , N _2, and N ₃ , there is a relationship of (the real part of N ₁ ) <(the real part of N ₃ ) <(the real part of N ₂ ).

Further, the width of the incident X-ray is W, the incident angle of the X-ray to the upper ruthenium layer 4 is φ, the film thickness of the upper ruthenium layer 4 is K ₁ , the film thickness of the lower ruthenium layer 2 is K ₂ , When the film thickness is D, the film thickness of the X-ray shielding layer 6 is K ₃ , and the focal length of the X-ray condenser lens is f, the X-ray shielding layer 6 has an X-ray whose end face on the X-ray entrance side is the carbon layer 3. It is arranged at an upstream position of (f + t (1) + W / sinφ) or more along the direction opposite to the traveling direction AX of the X-ray beam from the end surface on the exit side. Further, K ₃ > W / cos φ, K ₁ <K ₂ , K ₃ , and the distance from the end surface on the X-ray entrance side of the carbon layer 3 to the end surface on the X-ray entrance side of the X-ray shielding layer 6 is There is a relationship of zero or more. Note that t (1) is the length of the X-ray phase shifter layer 5 in the beam traveling direction, and details of this t (1) will be described later.

The X-ray phase shifter layer 5 of the X-ray condenser lens is orthogonal to the traveling direction AX of the X-ray beam from the center of the X-ray beam when the wavelength of the X-ray is λ and the focal length of the X-ray condenser lens is f. The distance along the direction AY is Y _n (Q / P) (where n is a zone index and P and Q are integers satisfying 1 ≦ Q ≦ P) and Y _n ((Q−1) / P) (Where (Q-1) / P> 0) and the end face on the X-ray entrance side extends in the direction opposite to the X-ray beam traveling direction AX from the X-ray waveguide exit 12 And f + t (1) is arranged upstream.

The distance (coordinates) Y _n (Q / P) from the center of the X-ray beam of the X-ray phase shifter layer 5 is obtained by the following equation.
Y _n (Q / P) = {nλf + 2λf (Q / P−1)} ^1/2 (4)
Further, the length t (Q / P) in the beam traveling direction of the X-ray phase shifter layer 5 is obtained by the following equation.
t (Q / P) = (Q−1) × λ / {P × (N ₃ −N ₁ )} (5)

1A and 1B show the case where P = 3. When P = 3, the distance (coordinates) from the center of the X-ray beam is Y _n (Q / P) (n = 0, 2, 4,..., Q / P = 1/3, 2 / 3 and 1), and the X-ray phase shifter layer 5 may be disposed in the black area of FIG.

  In the present embodiment, in order to prevent X-rays leaking from the cladding layer, the thickness of the lower ruthenium layer 2 and the X-ray shielding layer 6 is 100 nanometers, the thickness of the upper ruthenium layer 4 is 10 nanometers, X The thickness of the carbon layer 3 through which the line passes is 10 nanometers.

Further, in order to efficiently collect the X-rays by the X-ray zone plate portion 10, the X-ray phase shifter layer 5 is lengthened or transmitted until there is no X-ray transmitting through the X-ray phase shifter layer 5. It is necessary to cause the X-rays to interfere with each other by aligning the phase at the focal point (X-ray waveguide exit 12). In the present embodiment, a technique is adopted in which X-rays interfere with each other at the same phase at the focal point. Therefore, in this embodiment, by estimating from the density of the carbon layer 3 of 3.5 g / cm ³ and the density of the X-ray phase shifter layer 5 of 10.5 g / cm ³ , when P = 3, Y _n The length t (1) of the X-ray phase shifter layer 5 in the region between (1) and Y _n (2/3) is 4.8 microns from equation (5), Y _n (2/3) and Y The length t (2/3) of the X-ray phase shifter layer 5 in the region between _n (1/3) is 2.4 microns, and the region between Y _n (1/3) and Y _n (0) is The length t (1/3) of the X-ray phase shifter layer 5 is zero.

In this estimation, as an approximate expression, t = λ / {3 × (N ₃ −N ₁ )} = λ / {3 × (δ ₃ −δ ₁ )}, δ ₃ = 1.3 × 10 ⁻⁶ ρ ₃ λ ² and a relational expression of δ ₁ = 1.3 × 10 ⁻⁶ ρ ₁ λ ² were used (see Non-Patent Document 9). Here, ρ ₃ is the density of silver constituting the X-ray phase shifter layer 5, and ρ ₁ is the density of carbon. When such a phase shifter layer of silver having an integral multiple of length t = 2.4 microns is provided in each zone of n = 0, 2, 4,... (N is an even number), the X-ray phases are aligned. be able to. Here, the wavelength λ of the incident X-ray is 0.154 nanometers. Moreover, the refractive index of each layer can be calculated | required from the wavelength (lambda) of X-ray, and the density of each layer (refer nonpatent literature 9). Incidentally, the densities of ruthenium, carbon and silver are 12.4, 3.5 and 10.5 g / cm ³ , respectively.

  Next, a method for manufacturing the X-ray condenser lens of the present embodiment will be described. First, the lower ruthenium layer 2 is formed on the silicon substrate 1 by vapor deposition, for example. Silver is deposited on the lower ruthenium layer 2 and then processed by a method such as electron beam lithography to form the X-ray phase shifter layer 5. Subsequently, the carbon layer 3 is formed on the lower ruthenium layer 2 by sputtering, for example. At this time, the thickness of the carbon layer 3 is set to be equal to or less than the thickness of the X-ray phase shifter layer 5. Subsequently, the upper ruthenium layer 4 is formed on the carbon layer 3 and the X-ray phase shifter layer 5 by, for example, vapor deposition. Finally, the X-ray condensing lens 6 is completed by forming the X-ray shielding layer 6 made of ruthenium on a part of the upper portion of the upper ruthenium layer 4 by vapor deposition, for example.

  When the X-ray beam 7 is incident on the upper ruthenium layer 4 of the X-ray condenser lens thus manufactured from the left side of FIGS. 1A and 1B at an incident angle φ, it is incident on the X-ray waveguide portion 8. Then, the transmitted X-rays pass through the X-ray waveguide portion 9 where the loss of X-rays is small, and then enter the X-ray zone plate portion 10. At this time, a part of the X-ray is phase-modulated by the three-stage phase shifter layer 5 arranged in each zone and reaches the X-ray condensing unit 11. Since the X-ray beam cannot spread in the direction perpendicular to the silicon substrate 1, the size of the X-ray beam in the vertical direction (vertical direction in FIG. 1B) is the same as in the case of the X-ray waveguide portions 8 and 9. It is about 10 nanometers.

  On the other hand, since there is nothing that restricts the mode of the X-ray beam in the horizontal plane of the waveguide, the X-rays emitted from the opening of the X-ray zone plate unit 10 are generated in the X-ray condensing unit 11 and in the one-dimensional Fresnel. The light travels through the zone plate structure and is condensed at the position of the X-ray waveguide outlet 12. The horizontal size of the X-ray beam at this time is determined by the minimum width of the X-ray phase shifter layer 5 (vertical dimension in FIG. 1A). On the other hand, the vertical beam size at the X-ray waveguide exit 12 is about 10 nanometers. Further, since the minimum value of the width of the X-ray phase shifter layer 5 is about 8 nanometers, the horizontal beam size is about 10 nanometers.

  In the present embodiment, by using the resonance beam coupling method, X-rays can be incident on the carbon layer 3 from the surface of the upper ruthenium layer 4 where the X-ray shielding layer 6 is not formed. X-rays can be introduced into the waveguide. Furthermore, in the present embodiment, the X-ray shielding layer 6 is formed on a part of the surface of the upper ruthenium layer 4 and the upper cladding layer is formed in a convex structure, so that the X-rays are totally reflected on the surface of the upper cladding layer. Can be shielded. Thus, in this embodiment, a coherent nanoscale X-ray condensed beam with less intensity unevenness and defocusing can be obtained.

  As exemplified above, in the X-ray condenser lens of the present embodiment, the X-ray beam can be focused in a point-like manner while effectively using the energy of the incident X-ray beam. Since an intense X-ray microbeam can be realized, advanced structural evaluation of nanometer level materials becomes possible.

  In this embodiment, compared with the X-ray condenser lens of the prior art 2 that uses a phase shifter layer in the X-ray waveguide structure, the condensing efficiency of the X-ray condenser lens is theoretically 1 when P = 3. In the case of 0.7 times (68.3%) and P = 4, it can be increased to about twice (81.2%), and an X-ray beam that can be easily used for analysis can be obtained. Note that the X-ray condensing lens of the prior art 2 corresponds to the case of P = 2, and the condensing efficiency at this time is 40.5%. In the present embodiment, in order to further improve the light collection efficiency, P may be an integer of 4 or more, and multistage X-ray phase shifter layers may be arranged in each zone where n is an even number.

  When the X-ray condenser lens of this embodiment is used for material evaluation, the light emitted from the X-ray condenser lens is directly irradiated to the material to be evaluated, or the light emitted from the X-ray condenser lens is further emitted. The material may be evaluated by collecting the light with a mirror and irradiating the material to be evaluated, or detecting X-rays diffracted by the material or fluorescent X-rays generated from the material.

  In addition, this invention is not limited to the above embodiment. For example, in the present embodiment, the X-ray phase shifter layer 5 is provided in the core layer of the X-ray waveguide, but may be provided outside the core layer. In this case, the X-ray phase shifter layer 5 may be provided so that the position of the end face on the X-ray entrance side is a position upstream from the X-ray waveguide outlet 12 by f + t (1).

  In this embodiment, carbon is used as the material for the core layer. However, the material for the core layer may be a material containing at least one of carbon, oxygen, silicon, beryllium, and a polymer material. Further, as the material of the core layer, a material containing at least one of boron, oxygen, aluminum, fluorine, calcium, magnesium, and titanium may be used, and polyimide, polymethyl methacrylate, fluorine resin, or chlorine resin is used. Also good.

  In this embodiment, ruthenium is used as a material for the cladding layer and the X-ray shielding layer, but any material containing at least one of tungsten, ruthenium, and tantalum may be used. In addition, as a material for the cladding layer and the X-ray shielding layer, a material containing at least one of nickel, cobalt, chromium, vanadium, titanium, germanium, molybdenum, zirconium, indium, rhenium, silver, gold, platinum, and tantalum is used. May be. The material of the X-ray phase shifter layer 5 may be the same as that of the clad layer, or a material different from the clad layer may be used among the materials mentioned as the clad layer material.

  In the present embodiment, silver is used as the material of the X-ray phase shifter layer 5, but tungsten, ruthenium, tantalum, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, palladium, silver, cadmium, indium, Material containing at least one of barium, rhenium, osmium, iridium, platinum, gold, lead, thallium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, or carbon, oxygen, silicon, beryllium, calcium Alternatively, a material containing at least one of scandium, titanium, vanadium, chromium, manganese, tellurium, and a polymer material may be used.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 3A is a plan view showing the configuration of the X-ray condenser lens according to the second embodiment of the present invention, and FIG. 3B is II of the X-ray condenser lens of FIG. FIG. 2 is a cross-sectional view, and the same components as those in FIGS. 1A and 1B are denoted by the same reference numerals. In FIG. 3A, it is assumed that the X-ray phase shifter layer 5 and the X-ray beam transmitted through the X-ray waveguide lens structure and the laminated Fresnel zone plate structure are seen through. Further, although the X-ray phase shifter layer 5 does not actually exist at the position of the II line in FIG. 3A, in FIG. 3B, in order to clarify the position of the X-ray phase shifter layer 5 The X-ray phase shifter layer 5 is described for convenience.

The X-ray condensing lens of the present embodiment includes an X-ray waveguide lens structure including an X-ray waveguide portion 8, an X-ray waveguide portion 9, an X-ray zone plate portion 10, and an X-ray condensing portion 11. A laminated Fresnel zone plate structure 15 called a one-dimensional Fresnel zone plate is formed on the same substrate.
In the example of FIGS. 3A and 3B, the traveling direction of the X-ray beam is AX, and the stacking direction of the core layer and the cladding layer of the X-ray waveguide lens structure is the direction orthogonal to the traveling direction AX. The direction orthogonal to AZ, AX and AZ is AY.

  Since the X-ray waveguide lens structure is the same as that of the first embodiment, description thereof is omitted. However, in the first embodiment, the position of the end surface on the X-ray entrance side of the X-ray phase shifter layer 5 is f + t (1) along the direction opposite to the traveling direction AX of the X-ray beam from the X-ray waveguide exit 12. Whereas the X-ray phase shifter layer 5 is disposed only upstream, in the present embodiment, the position of the end face on the X-ray entrance side is only f + t (1) from the focal point 16 of the X-ray condenser lens. The X-ray phase shifter layer 5 is disposed so as to be located upstream.

The stacked Fresnel zone plate structure 15 is a structure in which heavy element layers 13 that hardly transmit X-rays and light element layers 14 that transmit X-rays are alternately stacked.
The heavy element layer 13 has a direction AZ perpendicular to the traveling direction AX of the X-ray beam from the center of the X-ray beam (II-II line in FIG. 3B) when the focal length as the condenser lens is f ₁ . Of the second region between the position of Z _2m (where m is 0, 1, 2,...) And the position of Z _{2m + 1} , the third region excluding this second region. It is arranged at any one of them, and is arranged upstream from the focal point 16 of the X-ray condenser lens by a focal length f ₁ along the direction opposite to the traveling direction AX of the X-ray beam. The distances (coordinates) Z _2m and Z _{2m + 1} from the center of the X-ray beam of the heavy element layer 13 are obtained by the following equations.
Z _2m = (2mλf ₁ ) ^1/2 (6)
Z _{2m + 1} = {(2m + 1) λf ₁ } ^1/2 (7)

FIG. 4 shows a case where the heavy element layer 13 is provided in the second region between Z _2m (m is 0, 1, 2,...) And Z _{2m + 1} . When the heavy element layer 13 is provided in the third region except between Z _2m and Z _{2m + 1} , the heavy element layer 13 is disposed between the black background regions of FIG. The light element layer 14 may be disposed.

  The manufacturing method of the X-ray waveguide lens structure including the X-ray waveguide portions 8 and 9, the X-ray zone plate portion 10 and the X-ray condensing portion 11 is substantially the same as that of the first embodiment. In the embodiment, the mesa structure is formed on the silicon substrate 1 by etching, and the lower ruthenium layer 2 is formed only on the mesa structure using a mask. The subsequent steps are as described in the first embodiment.

Next, a manufacturing method of the laminated Fresnel zone plate structure 15 of the present embodiment will be described. The position of the distance L + t (1) downstream from the end face on the X-ray entrance side of the X-ray phase shifter layer 5 along the traveling direction AX of the X-ray beam is the end face on the X-ray exit side of the laminated Fresnel zone plate structure 15. Thus, the heavy element layer 13 made of tungsten and the light element layer 14 made of tungsten silicide are alternately formed by, for example, sputtering. In the present embodiment, the heavy element layer 13 is provided in the second region between Z _2m shown in Formula (6) and Z _{2m + 1} shown in Formula (7). At this time, the X-ray beam incident from the X-ray waveguide lens structure is arranged so that the position of the center in the AZ direction (II-II line in FIG. 3B) coincides with the center of the heavy element layer 13 at the center. To do. This completes the production of the X-ray condenser lens.

  When the X-ray beam 7 is incident on the X-ray condenser lens thus manufactured from the left side of FIGS. 3A and 3B, it proceeds in a waveguide mode depending on the length of the X-ray waveguide lens structure. Although the presence of X-rays other than X-rays may not be ignored, in this embodiment, the length of the X-ray waveguide lens structure and the length of the laminated Fresnel zone plate structure 15 are each 10 millimeters. Since this value is sufficiently larger than the wavelength of the X-ray, only the X-ray beam that passes through the X-ray waveguide lens structure satisfies the formula (1), and the direction perpendicular to the silicon substrate 1 is present. The size of the X-ray beam in the vertical direction (FIG. 3B) is about 10 nanometers.

  The principle of X-ray focusing by the X-ray waveguide lens structure including the X-ray waveguide sections 8 and 9, the X-ray zone plate section 10 and the X-ray focusing section 11 is as described in the first embodiment. is there. The difference from the first embodiment is that the horizontal condensing position is changed from the X-ray waveguide exit 12 shown in FIGS. 1A and 1B to the focal point 16.

  The vertical size of the X-ray beam at the exit 12 of the X-ray waveguide lens structure is about 10 nanometers. The X-ray beam emitted from the outlet 12 is emitted in the vertical direction with a divergence angle that is twice the incident angle. This X-ray beam is condensed again by the laminated Fresnel zone plate structure 15 disposed behind the X-ray waveguide lens structure.

  On the other hand, the X-rays emitted from the X-ray zone plate portion 10 of the X-ray waveguide lens structure travel through the X-ray condensing portion 11 and the laminated Fresnel zone plate structure 15 as a one-dimensional spherical wave. As a result, the X-rays traveling through the X-ray condensing unit 11 and the laminated Fresnel zone plate structure 15 are condensed in the horizontal direction (up and down direction in FIG. 3A) by the interference effect.

Therefore, if the position of the focal point 16 by the X-ray zone plate part 10 and the X-ray condensing part 11 of the X-ray waveguide lens structure and the condensing position by the laminated Fresnel zone plate structure 15 are made to coincide, A distance can be taken between the condenser lens and the focal point 16.
In the X-ray condensing lens of the first embodiment, since X-rays are condensed on the end face of the X-ray waveguide, it is difficult to adjust a minute part depending on the shape of the sample when measuring a sample having a three-dimensional structure. It is. That is, in the X-ray condenser lens of the first embodiment, if the sample is placed at a location away from the end face of the X-ray waveguide, the X-ray emitted from the waveguide is perpendicular to the traveling direction. Since the direction again becomes divergent light and irradiates the sample, the characteristics of the nanobeam condensed by the X-ray condenser lens cannot be used effectively.

  On the other hand, in the present embodiment, the working distance between the X-ray condenser lens and the sample is sufficiently ensured by arranging the laminated Fresnel zone plate structure behind the X-ray waveguide lens structure. However, it is possible to realize beam condensing with a diameter of nanometer level. Thereby, in this Embodiment, the freedom degree of the alignment at the time of sample measurement can be raised.

  In this embodiment, tungsten is used as the material of the heavy element layer 13, but the material of the heavy element layer 13 is Ru, Ta, Rb, Sr, Y, Zr, Nb, Mo, Pd, Ag, Any material containing at least one of Cd, In, Ba, Re, Os, Ir, Pt, Au, Pb, Tl, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn may be used. Further, tungsten silicide is used as the material of the light element layer 14, but the material of the light element layer 14 is C, O, Si, Be, Ca, Sc, Ti, V, Cr, Mn, Te, a polymer material. A material containing at least one of them may be used, and polyimide, polymethyl methacrylate, fluorine resin, or chlorine resin may be used.

  The present invention can be applied to an X-ray condensing device.

It is the top view and sectional drawing which show the structure of the X-ray condensing lens which concerns on the 1st Embodiment of this invention. It is a top view for demonstrating the position of the X-ray phase shifter layer in the 1st Embodiment of this invention. It is the top view and sectional drawing which show the structure of the X-ray condensing lens which concerns on the 2nd Embodiment of this invention. It is sectional drawing for demonstrating the position of the heavy element layer of the laminated | stacked Fresnel zone plate structure in the 2nd Embodiment of this invention. It is the top view and sectional drawing which show the structure of the conventional X-ray condensing lens.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Lower ruthenium layer, 3 ... Carbon layer, 4 ... Upper ruthenium layer, 5 ... X-ray phase shifter layer, 6 ... X-ray shielding layer, 7 ... X-ray beam, 8 ... X-ray waveguide part , 9 ... X-ray waveguide part, 10 ... X-ray zone plate part, 11 ... X-ray condensing part, 12 ... X-ray waveguide outlet, 13 ... heavy element layer, 14 ... light element layer, 15 ... stacked Fresnel Zone plate structure, 16 ... Focus point of X-ray condenser lens.

Claims (5)

An X-ray condensing lens that collects X-rays using an X-ray waveguide in which an X-ray refractive index is N _{1 and} a core layer is sandwiched between clad layers having an X-ray refractive index of N ₂ .
The refractive index made of a material that transmits a part of the core layer to which X-rays enter or the X-ray is transmitted is N ₃ (the real part of N ₁ <the real part of N ₃ <N ₂ The phase shifter layer of the real part) and an X-ray shielding layer having a refractive index of N ₂ or more formed on a part of the surface of the upper cladding layer formed on the core layer,
The phase shifter layer has an X-ray wavelength of λ and a focal length of f, the traveling direction of the X-ray beam in the core layer is AX, and the core layer and the cladding layer out of the directions orthogonal to the traveling direction AX Is AZ, the direction perpendicular to the AX and AZ is AY, and the distance from the center of the X-ray beam along the AY direction is Y _n (Q / P) = {nλf + 2λf (Q / P−1)} ^{When 1/2} (n is a zone index and P and Q are integers satisfying 1 ≦ Q ≦ P), the position of Y _n (Q / P) and Y _n ((Q−1) / P) ( However, it is disposed along the AY direction in the first region between the positions (Q-1) / P> 0), and the length t (Q / P) of the phase shifter layer in the AX direction is An X-ray condenser lens, wherein t (Q / P) = (Q−1) × λ / {P × (N ₃ −N ₁ )}. The X-ray condenser lens according to claim 1,
The phase shifter layer is disposed such that the position of the end face on the entrance side is upstream by f + t (1) along the direction opposite to the traveling direction from the focal point of the X-ray condenser lens. X-ray condenser lens. The X-ray condenser lens according to claim 1 or 2,
The X-ray shielding layer has an incident angle of the X-ray beam to the upper cladding layer φ, the width of the X-ray beam W, the thickness of the upper cladding layer K ₁ , and the thickness of the core layer D When the thickness of the lower clad layer formed under the core layer is K ₂ , the position of the end surface on the inlet side extends from the end surface on the outlet side of the core layer along the direction opposite to the traveling direction (f + t (1) The X-ray shielding is performed such that the distance from the position of the end face on the inlet side to the position of the end face on the inlet side of the core layer is 0 or more. The X-ray condenser lens is characterized in that the layer thickness K ₃ satisfies K ₃ > W / cos φ. The X-ray condenser lens according to claim 1,
Furthermore, a laminated Fresnel zone plate structure disposed behind the X-ray waveguide including the phase shifter layer,
The laminated Fresnel zone plate structure is a structure in which a heavy element layer made of a material that does not transmit X-rays and a light element layer made of a material that transmits X-rays are alternately stacked. When the focal length of the type Fresnel zone plate structure is f ₁ , the distance along the AZ direction from the center of the X-ray beam is (2mλf ₁ ) ^1/2 (m is 0, 1, 2,...) And the second region between the position of {(2m + 1) λf ₁ } ^1/2 and the third region excluding the second region, X Line condensing lens. The X-ray condenser lens according to claim 4 ,
The exit-side end face of the laminated Fresnel zone plate structure is located at a distance L + t (1) downstream from the entrance-side end face of the phase shifter layer along the X-ray beam traveling direction AX.
An X-ray condenser lens, wherein a relationship of f = f ₁ + L is established between a focal length f of the X-ray waveguide and a focal length f ₁ of the laminated Fresnel zone plate structure.

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