JP2003515728A - X-ray zoom lens - Google Patents

Abstract

An optical array for focusing X-rays comprises a plate (made, for example, of silicon) on which a series of concentric circles are formed to form channels through the plate. -Shaped gap is etched. When X-rays are incident on the plate, they are reflected from inside the channel to the focal point. This plate is preferably curved to increase the magnification.

Description

Detailed Description of the Invention

The present invention relates to X-ray optics, and more particularly, the present invention relates to optical devices capable of focusing electromagnetic radiation in the frequency range commonly referred to as X-rays.

Focused X-rays are used for manufacturing microchips and micromachines.
-Ray lithography, spatially resolved X-ray fluorescence analysis, subcellular probe method (sub-cell)
It has and has the potential to be used in a wide range of applications such as ural probing), X-ray microscopy, and fabrication of scientific instruments. These applications require a powerful x-ray source and the ability to focus x-rays can increase the available source intensity.

Known methods for producing focused X-rays include the use of diffractive optical components (zone plates) and multilayer mirrors. While zone plates can form high resolution images, zone plates and multilayer mirrors
It has some drawbacks such as low efficiency, the need for monochromatic illumination, and a small aperture in the zone plate.

Although grazing incidence reflection optics are widely used in some applications, grazing incidence reflection optics are used in high resolution imaging systems due to their aberrations. I have never played. The system mainly used for hard X-ray applications is Kirkpatrick-Ba.
ez optics, Wolter optics, microcapillary optics, polycapillary (
polycapillary optics, as well as microchannel plate arrays.

MA Kumakov (1998 Proc. SPIE 3444 424-
429), and HN Chapman, KA Nugent, SW W.
ikins (1991 Rev. Sci. Insrum. 62 1542-15)
61), the polycapillary optics described above uses a series of curved small channels (10 ^-6 m) along which X-rays are propagated and It uses grazing incidence line reflection to focus the. Although polycapillary optics have large apertures, large bandpass, and high propagation efficiencies, they are difficult to design and fabricate while overcoming some constraints. These constraints include the restriction that the channel width, cross-sectional shape and curvature should cause only a few reflections (ideally only two) along each channel. This is because, if the number of reflections exceeds two, the correspondence between the object and the conjugate point of the image may be lost.
Therefore, it is necessary to change the channel width, shape, and curvature along the length direction of the channel. The open area of the channel at the entrance position of the optical device occupies a large percentage (> 80%) to the total area, but the large open area makes the optical device extremely fragile and the reflection due to the surface roughness. Variations in rate, absorption and scattering are disadvantages.

The inventors have devised X-ray optics based on microstructured optical arrays (MOA) that overcome many of the drawbacks of existing systems. Furthermore, most importantly, this optical system can be used as an X-ray zoom lens, which allows variable magnification and focal length control.

According to the invention there is provided an optical array comprising a plate, the surface of which is formed by a plurality of X-ray transparent zones separated by X-ray opaque bands. The band opaque to the line is of such a thickness that when an X-ray beam from a source is projected onto the plate, at least some of the X-ray is reflected from the outermost wall of the band. Also provided is an optical array in which there are control means capable of shaping the plate to form a curved surface on which X-rays passing through the plate can be focused.

In another aspect, an optical array comprising a plurality of x-ray opaque bands separated by x-ray transparent zones, the x-ray opaque bands comprising: Dimensioned such that when an X-ray beam from a source is projected onto the array, at least some of the X-rays are reflected from the walls of the band, and the angle of reflection of the X-rays can be dynamically changed. An optical array is provided that is deformable.

Further provided is a method of focusing an X-ray beam utilizing an optical array according to the present invention. The thickness of a band that is opaque to X-rays means the distance measured from the base of the band to its top, that is, the height above the adjacent X-ray transparent zone.

Preferably, the zones are in the form of a ring and the structure comprises x-ray transparent channels separated by x-ray opaque walls. The rings on the plates can be in the form of concentric circles, and the rings can be oval, oval, etc.

Preferably, these walls have a height such that there is at least one reflection in each channel, and for flat thin plates, the X on the outer wall of the channel. The line incidence angle can be slightly changed for one-to-one imaging, but the channel diameter must be small to reduce loss due to non-reflecting X-rays. However, if the channel diameter is too small, some of the x-rays may be lost by being reflected twice by both walls of the channel. Thicker plates can introduce aberrations as the angle of incidence changes along the channel, but pass through less X-rays.

The size of the plate will be determined according to its application. The width of the channel is preferably increased radially outward to allow for a large angle of incidence, and the width of the channel is compared to the width of the x-ray opaque section between the channels. It is preferable to make it wider. The width of the channel will be determined according to its application.

The plate may be etched directly into a substrate formed of a material that is opaque to X-rays, with channels transparent to X-rays penetrating the plate. It can be formed by depositing a ring of material opaque to X-rays in the form of a plate or a membrane and depositing the structure according to the invention.

When forming the structure on a plate or a film, a lost molding method (los) is used.
t mould process) can be used. In this method, structures sized and shaped for optical arrays are fabricated in a removable material (eg, by melting) and a mold is formed from the structures to remove the material. Next, the mold is used to form the optical array of the present invention.

Materials that can be used to form this array include metals such as nickel, and these can optionally be supported on a substrate. This channel wall must be smooth to prevent a loss of reflectivity. Typical roughness should be less than a fraction of a wavelength and can be achieved with electroplated nickel for X-rays.

Other suitable materials from which this plate can be made include silicon,
Silicon carbide is included, and the plate can be formed from a single silicon wafer of the type manufactured and marketed by Virginia Semiconductor, Inc. (Virginia semiconductor Inc.). Such silicon wafers can be patterned, for example by isotropic plasma etching, lithography, etc., to form the structures according to the invention.

In order to focus the X-rays that propagate through the plate, the plate is curved, and the greater the degree of curvature, the shorter the focal length of the array. This curvature is spherical, parabolic, etc., and the degree of this curvature can be varied depending on the wavelength of the X-ray, the distance from the plate to the X-ray source, the purpose of the focused X-ray beam, and the like. it can. The degree of curvature (and thus the achievable magnification) depends on the elasticity and stability of the plate material under bending stress.
ty). The ability to change the curvature makes it possible to obtain an X-ray zoom lens.

The plate can be curved by any suitable method, either before or after formation of the structure according to the invention. For example, if the plate is made of silicon, one method of forming the curvature in the plate is to use a silicon wafer after patterning to obtain a biomorph stress-induced curvature. The application of a prestressed layer on top. For example, the radial ribs of silicon are coated with a thin metal film that is in a compressive stress state when cooled. The degree of curvature (and thus the focusing distance of the structure) can be altered by changing the temperature at a particular point, for example by locally heating using a small heater.

Another way to bend the plate is to apply a differential pressure across the plate so that the plate bends. For example, the structure according to the present invention allows a plate mounted in an X-ray transparent sealed chamber containing helium to be lithographically formed on a silicon wafer to alter the differential pressure on one or both sides of the plate. The degree of curvature can be changed by.

Another way to bend the plate is to coat it with a piezoelectric material and change the curvature of the plate by varying the current applied to the piezoelectric material. Whichever method is used, the ability to change the curvature makes it possible to form an X-ray zoom lens, and to provide an X-ray beam focused by focusing X-rays while controlling the degree of concentration. You can Therefore, according to the MOA of the present invention, existing applications and potential applications such as X-ray lithography, space-resolved X-ray fluorescence analysis, subcellular probe method, and X-ray microscopy, as well as scientific instrument fabrication and imaging X-ray microscopy It is possible to obtain enhanced performance in space-resolved fluorescence microscopy, photoemission microscopy and astronomy.

The present invention is not wavelength-specific and can be used with hard X-rays and soft X-rays in a wavelength range including a wavelength range usually called extreme ultraviolet (EUV). The present invention is illustrated in the accompanying drawings.

In the drawing, even if there may be a plurality of reflections actually, it is represented by one reflection. Referring to FIG. 1, the plate (1) formed by the silicon wafer (3) is
Gap (3) etched on its surface by isotropic plasma etching
And a series of concentrically arranged X-ray opaque bands (2) of silicon and a gap (4) transparent to X-rays. The gap (3) is made wider compared to band (2), resulting in one open cobweb structure. In reality, the number of bands is much higher than shown. This plate can be produced by depositing the band (2) on the substrate (1).

X-rays from the radiation source A are incident on the plate (1), and the X-rays are reflected by the inner surface of (2) and are focused on the point B as shown in the figure. Referring to FIG. 2, the plate (5) is curved as shown so that the X-rays from the source A are focused at point (B) so that the X-rays are concentrated.

Referring to FIG. 4, in order to bend the plate (7), radial ribs (6) are formed of a metal such as nickel and the plate (7) is cooled when the metal is cooled.
7) is curved so that biomorph-induced stress is generated so as to form the shape shown in FIG.

If these ribs are coated with a piezoelectric material, the curvature can be electrically controlled by changing the current applied to this coating. Alternatively, the plate can be curved by local heating.

Referring to FIG. 5, the two sections (9a) and (9b) of the plate (
8) Plates (8) are sealed by pressure chambers (9) separated by
Place it inside. The chamber is sealed by pressure sealing caps (10) and (11), and helium is sealed in the sections (9a) and (9b). By increasing the pressure PA of (9a) with respect to PB (9b), the plate (8) undergoes bending as shown. One of sections (9a) or (9b) can also be exposed to atmospheric pressure.

Each of the above allows for various curvatures, which changes the focusing point B of the X-rays from the source A and shortens them to increase the magnification and the role of the X-ray zoom lens on this plate. Can be fulfilled.

[Brief description of drawings]

[Figure 1]   FIG. 7 is a side view schematic of a flat MOA.

[Fig. 2]   FIG. 7 is a side view schematic of a curved MOA.

[Figure 3]   FIG. 3 is a front view of FIG. 2.

[Figure 4] It is a front view showing use of a biomorph.

[Figure 5]   FIG. 6 is a schematic diagram of using pressure to bend a MOA.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Inventor Prewet, Philip Doughty             United Kingdom Birmingham Bee 15 2 tee             Tee, Edg Baston, School Oh             BU Manufacturing and             Mechanical Engineering, The Uni             Varsity of Birmingham F term (reference) 2H097 AA16 CA06 CA15 LA10 LA12                       LA20                 5F046 GB02

Claims (18)

[Claims] 1. An optical array comprising a plate, the surface of which is formed by a plurality of X-ray transparent zones separated by X-ray opaque bands. The opaque band is thick enough to reflect at least some of the x-rays from an outermost wall of the band when the x-ray beam from a source is projected onto the plate; An optical array having control means capable of forming a curved surface that can be shaped to focus X-rays that pass through the plate. 2. The X-ray transparent zone is in the form of a ring,
The optical array of claim 1, wherein the structure comprises a plurality of x-ray transparent channels separated by x-ray opaque walls. 3. The optical array of claim 2, wherein the rings on the plate are in the form of concentric circles or ellipses. 4. The optical according to claim 1, wherein the X-ray opaque band has a thickness such that there is at least one reflection in each channel. array. 5. An optical array according to any of claims 1 to 4, wherein the width of the channels widens radially outward to increase the incidence of incidence. 6. The optical array according to claim 1, wherein the width of the channels is wider than the width of a section opaque to X-rays between the channels. 7. The plate according to claim 1, wherein the plate is made of silicon.
The optical array according to any one of 1. 8. The optical array according to claim 1, wherein the plate is made of electroplated nickel. 9. An optical array, such as an X-ray zoom lens comprising an array according to any of claims 1 to 8, wherein said control means is such that the amount of curvature of said plate is changed. An optical array capable of forming an X-ray lens which is controllable and whose focal length is controlled by said control means. 10. Radial ribs of silicon or some metal attached to or forming a part of said plate, said control means comprising:
ribs), the ribs of silicon or some metal being in a compressive stress state when cooled and forming the plate in a curved shape.
The optical array according to. 11. The optical array of claim 9, wherein the control means comprises means for applying a differential pressure across the plate. 12. The control means comprises a piezoelectric material which is in contact with the plate or forms part of the plate, wherein the curvature of the plate is changed by fluctuations in the current applied to the piezoelectric material. The optical array according to claim 9, wherein the optical array is adapted to perform. 13. The optical array of claim 12, wherein the control means comprises local heating means. 14. An optical array, such as an X-ray zoom lens comprising an array according to any of claims 1 to 13, wherein said control means is such that the amount of curvature of said plate is changed. An optical array capable of forming an X-ray lens which is controllable and whose focal length is controlled by said control means. 15. An apparatus for using X-rays incorporating an array according to any of claims 1-14. 16. The apparatus according to claim 15, wherein the apparatus is X-ray lithography, space-resolved X-ray fluorescence analysis, subcellular probe method, X-ray microscopy, imaging X-ray microscopy, space-resolved fluorescence. A device selected from devices for microscopy, photoemission microscopy, and astronomy. 17. An optical array comprising a plurality of X-ray transparent zones separated by X-ray opaque bands, the X-ray opaque bands from a source. Sized to reflect at least some portion of the x-rays from a wall of the band when the x-ray beam is projected onto the array, and
An optical array dimensioned to be deformable so that the line reflection angle can be dynamically changed. 18. A method of focusing an X-ray beam such that the optical array according to any of claims 1 to 14 or 17 is placed in the path of the X-rays.