Microstructured transmission grating for x-ray radiation and corresponding production method

Abstract

Embodiments of the present invention comprise a method for producing a microstructured transmission grating for X-rays, the method comprising the following steps: providing a substrate and generating a grating structure by structuring a plurality of periodically arranged cavities in a first main surface of the substrate, wherein individual webs of substrate material remain between the cavities, and filling the cavities with a plurality of particles in the form of loose, dry powder. The substrate exhibits a lower absorption of X-rays than the particles.

Description

Technical area

[0001] Embodiments according to the present invention include microstructured transmission gratings for X-ray radiation, wherein the grating structure of the transmission grating comprises, among other things, a plurality of particles with a high X-ray absorption, as well as associated manufacturing methods. Background of the invention

[0002] A current technical problem is the reliable and economical production of transmission gratings for X-ray light. Analogous to transmission gratings for visible light, transmission gratings for X-ray light, for example, consist of a large number of alternating radiation-transmissive and opaque lines. The particular challenge is the production of the X-ray-opaque (i.e., absorbing) lines, as these must be made of a suitable material. For the technical application of these gratings, e.g., for clinical dark-field radiography, large grating areas of up to 1600 cm² are necessary, which places high demands on the corresponding manufacturing processes. State of the art

[0003] Conventional approaches include LIGA (lithography, electroplating, and molding) techniques, in which, after developing a photoresist using a galvanic process, a metallic seed layer is applied, onto which an X-ray absorbing material is subsequently deposited. However, the chip area that can be produced using LIGA is limited to a few square centimeters and low throughput. Furthermore, LIGA requires a synchrotron to expose the photoresist. This leads to very high process costs. To prevent deformation of the photoresist structures, they must also be periodically connected with bridges, which increases the manufacturing effort.

[0004] Other approaches include the fabrication of X-ray transmission gratings in silicon substrates using etching processes followed by electroplating of the X-ray absorber. However, such approaches require complex cleanroom processing after etching.

[0005] Furthermore, only a few electroplating processes are available for the deposition of X-ray absorbing materials, so that only a limited selection of materials can be used in both of the previously discussed approaches. Furthermore, these approaches require very long process times for electroplating and carry a high risk of process deviations.

[0006] Other conventional approaches include the production of X-ray transmission gratings by introducing metal particles in a solvent (suspension) into microcavities. In the first step, grating structures are patterned into silicon substrates using an etching process. In the second step, the metal particles dissolved in the moist suspension are applied to the grating structures, and the substrate is placed in an (ultra)centrifuge. The moist metal particles are then driven into the grating gaps by centrifugation. In the next step, the solvent is evaporated, and the particles are mechanically fixed using a binder added to the suspension. Finally, the surface of the grating structures is mechanically cleaned of any metal particles resting on the structure.

[0007] The Figures 8a) to 8c) show an example of such a process flow for the production of an X-ray transmission grating by centrifugation of a moist metal particle suspension. Fig. 8a ) shows grid sections before (left) and after (right) a cleaning process. Fig. 8b ) shows a corresponding grid after the cleaning process and Fig. 8c ) shows an enlarged section of the view from Fig. 8b ).

[0008] As in Fig. 8c ), this manufacturing process results in undesirable voids forming between the metal particles, which can be explained by the inclusion of gas bubbles in the suspension. Furthermore, laterally inhomogeneous filling of the lattice structures can occur due to variations in the particle suspension. Furthermore, such an approach imposes high mechanical stress on the substrates during centrifugation and poses significant challenges for process automation.

[0009] Therefore, it is an object of the present invention to provide a concept for a transmission grating for X-ray radiation, as well as an associated manufacturing method, which enables an improved compromise in terms of efficiency, complexity and reliability.

[0010] This object is achieved by the subject matter of the independent patent claims. Further developments according to the invention are defined in the subclaims. Summary of the invention

[0011] Embodiments according to the present invention comprise a method for producing a microstructured transmission grating for X-rays, wherein the method comprises the following steps, which in principle can also be carried out in a different order than that specified here: providing a substrate and creating a grating structure by structuring a plurality of periodically arranged cavities in a first main side of the substrate, with individual webs of substrate material remaining between the cavities, and filling the cavities with a plurality of particles in the form of loose, dry powder. The substrate has a lower absorption for X-rays than the dry particle powder.

[0012] Furthermore, embodiments according to the present invention comprise a microstructured transmission grating for X-rays. The transmission grating comprises a substrate with a grating structure, wherein the grating structure comprises a plurality of alternately arranged first and second grating sections. Furthermore, the first grating sections comprise a plurality of particles in the form of loose, dry powder and / or in the form of particles solidified by means of a coating. Furthermore, the first grating sections exhibit a higher absorption for X-rays than the second grating sections, thus forming the microstructured transmission grating for X-rays.

[0013] Optionally, the substrate further comprises a plurality of periodically arranged cavities in which the particles of the respective first lattice sections are at least partially arranged.

[0014] Embodiments according to the present invention are based on the core idea of ​​producing the X-ray-absorbing material of the transmission grating using a loose, dry powder. It has been recognized that a variety of materials suitable for X-ray absorption can be provided in powder form, and that corresponding powders can also be processed to produce grating structures with little effort compared to conventional techniques. As explained above, the powder can, for example, be filled into cavities of a substrate in order to form X-ray-absorbing grating lines of the transmission grating. The powder can thus serve as an X-ray-absorbing absorber powder and form first grating sections of the transmission grating.Substrate webs remaining between the cavities can form second grating sections which are arranged alternately with the first grating sections, resulting in a transmission grating with a plurality of alternately arranged first and second grating sections.

[0015] The use of the X-ray absorbing material in the form of a loose, dry powder enables particularly simple, fast, and reliable filling of the cavities. This means that, compared to the state of the art, no slow electroplating processes are necessary. This also allows the technological effort required for production to be kept low, since only the loose, dry powder needs to be filled into the cavities. This allows, for example, even "thick" X-ray absorbing grating lines to be produced with little effort, since a corresponding thickness (e.g., of at least 100 µm) can only depend significantly on the production of the cavity (into which the powder is "simply" filled) and not on a deposition process.

[0016] Thus, a transmission grating according to the invention can be manufactured in a short time, but also with high reliability. The manufacturing precision with regard to the geometry of the grating, for example, depends only significantly on the production of the cavities into which the powder is poured. There is no dependence on, for example, electroplating process parameters or binding agents. Furthermore, expensive and complex centrifugation is not necessary. In particular, this minimizes mechanical stress on the substrate and the X-ray absorbing material.

[0017] It was also discovered that using loose, dry powder can also achieve a high degree of homogeneity in the X-ray absorbing structures, such as the first lattice sections. The powder can optionally be further compacted in the cavities to prevent possible gas inclusions.

[0018] At this point, it should be noted that optionally the substrate webs can be partially removed and / or replaced with another material, and the loose, dry powder can be solidified and / or partially solidified into porous bodies by means of a coating.

[0019] The powder may, for example, be in the form of a granular material or in the form of a powder. In other words, such powders may comprise or be formed from a large number of small particles. The particles may have an average or maximum particle size of less than 50 µm, or less than 25 µm, or less than 15 µm, or less than 5 µm, or less than 1 µm.

[0020] According to embodiments of the present invention, the method further comprises at least solidifying the loose, dry powder located within the cavities. The particles present in powder form can be completely or only partially solidified. This (partial) solidification can be carried out using a coating process, wherein a coating material used here penetrates into the cavities between individual particles and thus firmly bonds the particles to one another. This results in solidified porous structural bodies that can have very high strength. According to the invention, at least some of the plurality of particles within the cavities can therefore be provided in the form of solidified porous bodies with higher X-ray absorption than the substrate.

[0021] In other words, the method optionally comprises at least partially solidifying the loose, dry powder located within the cavities using a coating process, wherein the powder solidified within a cavity forms a solidified porous body in the respective cavity, and wherein the respective solidified porous bodies have a higher X-ray absorption compared to the substrate.

[0022] According to embodiments of the present invention, the at least partially solidified particles can be present both in the form of unsolidified, loose, dry powder and in the form of particles solidified into porous bodies by means of the coating. The unsolidified, loose, dry powder can be arranged in the cavities, enclosed between the solidified particles and the substrate.

[0023] For example, the solidified particles can be used to create a kind of "plug" in the respective cavities to prevent the loose, dry powder contained in the respective cavity from falling out. The solid porous bodies formed by the solidified particles can thus be located, in particular, at an end of the respective cavity facing away from the substrate. This can result from the coating material used in the coating process penetrating the cavities from top to bottom, thus coating the particles located in the cavities from top to bottom. The coating process can be controlled so that only an (upper) portion of the particles is coated and solidified, or so that all of the particles are completely coated and solidified.Accordingly, in the case of partial solidification, the loose, dry powder remaining uncoated in a cavity can be located at a (lower) end of the cavity facing the substrate. Optionally, the coating material can also be used to attach a solid, porous body created with it to an inner wall of the cavity. The inner wall of the cavity can consist of substrate material, formed, for example, from ridges left over from the structuring of the cavities, or of another material, e.g., a filler or potting material with which removed or partially removed substrate ridges were replaced.

[0024] In a transmission grating according to the invention, the particles can therefore be partially or completely in the form of particles solidified into porous bodies by means of the coating, wherein these solidified porous bodies can each form the first grating sections.

[0025] Through complete solidification, the stiffness and / or mechanical stability of the transmission grating can be increased. Furthermore, the coating allows the first grating structure to be robustly secured in the cavity, since the coating can secure the individual grating lines—for example, the webs comprising the solidified particles—in the cavity down to a base structure.

[0026] According to embodiments of the present invention, the coating process can be carried out using a liquid polymer. Alternatively or additionally, the coating process can involve the deposition of organic or inorganic substances from a gas phase, e.g., by means of chemical vapor deposition (CVD) or, for example, by means of atomic layer deposition (ALD). In particular, atomic layer deposition allows the coating to penetrate into the spaces between the particles and to bond the particles at their contact points in a mechanically robust and reliable manner.

[0027] According to embodiments of the present invention, the method further comprises applying a cover layer to the lattice structure or to the first main side of the substrate to enclose the plurality of particles in the cavities. According to embodiments, the cover layer can thus be arranged on the lattice structure to enclose the particles in the first lattice sections.

[0028] The cover layer can be applied alternatively or in addition to the above-described solidification of the loose, dry powder. The cover layer can cover loose, dry powder located in the cavities or in the first grid sections, or cover it so that the powder is enclosed and thus secured in the respective cavity. The cover layer, in turn, can contain a plurality of particles in the form of loose, dry powder and / or in the form of solidified or agglomerated particles to enclose the underlying particles in the cavity. In this case, a porous body arranged at an end facing away from the substrate can serve, together with the cover layer, as a "double lid" for the loose, dry powder. For the sake of completeness, it should also be mentioned that the application of a cover layer is also possible in the case of fully solidified or agglomerated powder in a respective cavity.

[0029] The application of the cover layer can include at least one of the following process steps: application of a mechanically stable film, e.g. a polymer film or a metal film such as a thin aluminum foil, application of a polymer layer (e.g. a liquid polymer layer and optionally subsequent curing of the polymer layer), and / or application of organic or inorganic substances deposited from the gas phase, e.g. by means of chemical and / or physical gas phase deposition or e.g. by means of atomic layer deposition.

[0030] When arranging the cover layer on the lattice structure, the loose, dry powder in the cavities can also be solidified, at least partially, by means of the cover layer material or the cover layer coating itself.

[0031] For the proper functioning of the transmission grating, it can be important that the substrate surface is largely free of particles of the absorbing material, especially in the area of ​​the substrate ridges between the X-ray absorbing grating lines. Accumulations of absorbing particles can locally negatively affect the absorption behavior of the transmission grating and thus cause imaging errors.

[0032] In order to remove particles from the substrate surface, a sacrificial layer can be used during production of the transmission grating. A photoresist or a silicon layer, for example, can serve as a sacrificial layer. The sacrificial layer can be applied and structured before the cavities are created so that the surfaces of the substrate, including the substrate webs, are fully or partially covered by the sacrificial layer before the particles are introduced. After the absorbing grating lines have been created, the sacrificial layer can be removed selectively from all other materials present using a suitable etching process. In this process, particles located on the sacrificial layer can be fully or partially detached or removed, leaving a clean substrate surface that is largely or completely free of particles.

[0033] Alternatively or additionally, the surface of the transmission grating can be ground and / or polished after application of a cover layer, for example, to remove absorbing particles outside the X-ray absorbing grating lines from the substrate surface.

[0034] According to embodiments of the present invention, the method further comprises thinning back a second main side of the substrate, opposite the first main side. This allows absorbing particles to be easily removed from the other side of the substrate as well. In addition, mechanical properties, such as a stiffness of the transmission grating, and / or optical properties, e.g. with regard to a beam path or a length of a corresponding beam path in the substrate material, can be adapted (e.g. in the case of backside irradiation). By producing the transmission grating by filling in particles and the optional coating, which e.g.can be carried out at different temperatures, the substrate can have only small internal stresses or other stress weak points, so that a structural weakening of the substrate is possible to adapt the properties of the transmission grating.

[0035] According to embodiments of the present invention, the method further comprises at least partially removing one or more of the webs made of substrate material. The webs can be formed starting from the first main side and / or from a second main side of the substrate opposite the first main side. This allows the mechanical and / or optical properties of the transmission grating to be adjusted. For example, removing web material between the first grating sections can reduce the rigidity of the transmission grating, making it easier to bend the transmission grating.

[0036] Areas where the substrate material webs have been completely or partially removed can be completely or partially filled with a filler material, whereby the filler material has a lower absorption for X-ray radiation than the adjacent loose or (partially) solidified particles. Using an appropriate filler material, which can also be an ambient fluid such as air, an X-ray absorption different from that of the substrate material can be adjusted to create the transmission grating with alternating grating sections with different radiation absorption. Alternatively or additionally, the filler material can be used to adjust mechanical properties.For example, a filler can be used that allows increased flexibility of the transmission grating, but at the same time serves as a spacer between the individual particle-containing sections (first grating sections), so that the spacers form flexible second grating sections, each arranged between the first grating sections. This means that the second grating sections can be formed at least partially by means of the filler.

[0037] For example, due to the removal of webs from the substrate, a transmission grating according to embodiments can optionally no longer have cavities in the substrate material. In particular, the cavities created during the manufacturing process can no longer be present in that they are filled with the particles. New cavities can be formed, for example, in the regions in which webs from the substrate material were removed, but these were not filled with filler. Accordingly, the particles can also be at least partially enclosed in cavities formed by filler and substrate.

[0038] In some embodiments, the first grating sections may partially protrude from the cavities in the substrate material. In this case, a corresponding first grating section would, for example, only be partially arranged in a cavity.

[0039] According to embodiments of the present invention, a respective cavity has an aspect ratio (width / depth) of at least 1:9 or at least 1:5. Furthermore, a grating period of the grating structure can optionally be less than 50 µm. For example, a distance between two consecutive first grating sections and / or two consecutive second grating sections with respect to a predefined irradiation direction for the X-ray radiation can be less than 50 µm. For example, in this case, the particles can in particular have average or maximum particle sizes of less than 50 µm, or less than 25 µm, or less than 15 µm, or less than 5 µm, or less than 1 µm.

[0040] According to embodiments of the present invention, the particles can comprise at least tungsten and / or bismuth and / or gold. Embodiments of the invention make it possible, in particular, to process tungsten efficiently, something that was previously impossible with previous methods. Using the method according to the invention, tungsten can be processed in the form of loose, dry powder with minimal technological effort to produce the first lattice sections described here, which exhibit a very high degree of absorption for X-rays.

[0041] According to embodiments of the present invention, the substrate may comprise or consist of at least one of the following materials: silicon, glass, sapphire, ceramic, or polymers. Thus, embodiments allow the use of common substrate materials and therefore offer good flexibility.

[0042] According to embodiments of the present invention, the first lattice sections may have a defect-free distribution of particles, wherein defects are cavities that are several times larger than an average pore size of the porous bodies. Short character description

[0043] Examples according to the present disclosure are explained in more detail below with reference to the accompanying figures. With regard to the schematic figures shown, it should be noted that the illustrated functional blocks are to be understood both as elements or features of the device according to the disclosure and as corresponding method steps of the method according to the disclosure, and corresponding method steps of the method according to the disclosure can also be derived therefrom. They show: Fig. 1 shows a schematic view of a microstructured transmission grating for X-rays according to embodiments of the present invention; Fig. 2 shows a schematic representation of an example of a filling process for a substrate having cavities with loose powder according to embodiments of the present invention; Fig. 3 a), b) shows schematic side views of transmission gratings with an optional cover layer and optionally solidified particles according to embodiments of the present invention; Fig. 4 a), b) shows schematic views of transmission gratings with an optionally thinned substrate and optionally partially removed substrate webs according to embodiments of the present invention; Fig. 5 shows a transmission grating according to embodiments of the present invention; Fig. 6 a)-h) shows schematic views of transmission gratings and associated intermediate products in a manufacturing process according to embodiments of the present invention;7 a)-t) schematic views of further optional configurations of transmission gratings according to embodiments of the present invention; and Fig. 8 a)-c) an example of an X-ray transmission grating produced by centrifuging a metal particle suspension. Detailed description of the examples according to the figures

[0044] Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same or similar reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0045] Fig. 1shows a schematic view of a microstructured transmission grating 100 for X-ray radiation according to embodiments of the present invention.

[0046] The transmission grating 100 comprises a substrate 110 with a grating structure 120. The grating structure 120 comprises a plurality of first and second grating sections 122, 124 arranged alternately next to one another. The first grating sections 122 contain or comprise a plurality of particles 130 (indicated only schematically here), which may be in the form of loose, dry powder and / or in the form of particles solidified by means of a coating. Furthermore, the first grating sections 122 have a higher absorption for X-rays than the second grating sections 124, thus forming the microstructured transmission grating 100 with different radiation absorption coefficients for X-rays.

[0047] In other words, the first and second grating sections 122, 124 are arranged alternately to form more strongly and less strongly absorbing lines of the transmission grating 100. The second grating sections 124 can have webs 114 made of substrate material or consist of such webs 114. As will be explained in more detail later, such webs 114 can also be completely or partially removed, and they can be completely or partially replaced by another material, e.g., by a filler or a potting material.

[0048] With reference to Fig. 1A manufacturing method according to exemplary embodiments will be further explained below. The method comprises providing the substrate 110 and creating a lattice structure 120 in or on the substrate 110. The lattice structure 120 can be created by structuring a plurality of periodically arranged cavities 112 into a first main side of the substrate 110, with individual webs 114 made of substrate material remaining between the cavities 112.

[0049] The cavities 112 can then be precisely those regions defined by the substrate 110 with successive webs 114. Furthermore, the method comprises filling the cavities 112 with a plurality of particles 130 in the form of loose, dry powder. The cavities 112 can be at least partially, but preferably completely, filled with the loose, dry powder.

[0050] According to the invention, the particles 130 have a higher absorption for X-rays than the substrate 110. Thus, a transmission grating 120 is produced which has alternating first grating sections 122 and second grating sections 124, wherein the first grating sections 122 have a higher absorption for X-rays than the second grating sections 124. The first grating sections 122 can be formed using the aforementioned particles 130, which are initially introduced into the cavities 112 in the form of loose, dry powder and can then optionally be solidified and / or partially solidified. The second grating sections 124 can be formed from the webs 114 of substrate material remaining between the cavities 112.

[0051] Both the cavities 112 filled with the particles 130 and the loose and / or (partially) solidified particles 130 themselves located in the cavities 112 can be referred to as first lattice sections 122 in the context of the present disclosure.

[0052] In the following, reference is made to the Figures 2 a), b) and 3 a), b) .

[0053] The Figures 2a) and 2b ) show a schematic representation of an example of a filling process of cavities present in a substrate with loose, dry powder according to embodiments of the present invention. Fig. 2a ) shows a substrate 210 with cavities 212, as well as a plurality of particles 230 in the form of a loose, dry powder. Fig. 2b ) shows the substrate 210 with filled particles 230, wherein the particle powder 230 largely completely fills the cavities 212.

[0054] The Figures 3a) and 3b) show schematic side views of transmission gratings 300a, 330b according to the invention with an optional cover layer 340a or optionally solidified particles.

[0055] Fig. 3a) shows a transmission grating 300a, comprising a substrate 310a and a grating structure 320a. The grating structure 320a has first grating sections 322a, which are formed by a large number of particles, which here are in the form of loose powder 330a, e.g., absorber powder. The grating structure 320a has second grating sections 324a, which are arranged between the first grating sections 322a and which can be configured, for example, in the form of webs made of substrate material. The transmission grating 300a can optionally have a cover layer 340a. The cover layer 340a can, for example, be configured in the form of a polymer film and / or in the form of a polymer, e.g., in the form of a curable epoxy resin. Alternatively or additionally, the cover layer 340a can be formed by means of organic or inorganic substances deposited from the gas phase, e.g., using a CVD process.

[0056] Fig. 3b) shows an alternative embodiment of a transmission grating 300b according to the invention with a substrate 310b and a grating structure 320b. Here, the first grating sections 322b are configured in the form of at least partially, or preferably completely, solidified particles 330b. The particles 330b, initially present in powder form, can be coated, for example, using atomic layer deposition (ALD), and thereby (partially) solidified. The (partially) solidified particles 330b of the originally loose, dry powder 330a can form a plurality of solid porous bodies, which can form the first grating sections 322b and thus the X-ray absorbing lines of the transmission grating 300b. Here, too, the second grating sections 324b can be formed in the form of webs made of substrate material.

[0057] Fig. 3b) thus shows an embodiment in which a previously loose absorber powder is converted into solid, porous structural bodies with high X-ray absorption by coating the powder particles using a suitable coating process (e.g., ALD). The coating mechanically bonds the particles 330a at their contact points. For mechanically bonding or solidifying the initially loose, dry powder bed, liquid polymers or organic or inorganic substances deposited from the gas phase (e.g., using an ALD process), for example, can be used. These penetrate into the spaces between the individual particles 330a and bond the particles 330a to one another at their respective contact points to form the at least partially, or preferably completely, solidified particles 330b.

[0058] The provisions of the Figures 3a) and 3b) can be combined with each other. This means that the Figure 3a ) loose particles below the cover layer 340a can be (partially) solidified. Likewise, on the Figure 3b ) shown lattice structure 320b, a cover layer 340a may be arranged.

[0059] All embodiments described herein comprise a substrate with a lattice structure. A planar substrate made of a material with low X-ray absorption can serve as the starting material. To create the lattice structure, the substrate can, for example, be provided with suitable, periodically arranged cavities (e.g., 112, 212) that are filled with loose, dry powder with high X-ray absorption (see Fig. 2a )).

[0060] Suitable substrate materials include silicon, glass, sapphire, ceramics, or polymers. Suitable powders include tungsten, bismuth, or gold. The periodicity of the lattice segments is, for example, a maximum of 50 µm. Optionally, the aspect ratio of the cavities is at least 9, preferably at least 5.

[0061] According to the invention, the loose powder (e.g. 112, 212, 330a) is introduced dry into the cavities (e.g. 112, 212) (see Fig. 2b )). Optionally, the loose powder can then be mechanically enclosed in the cavities by a suitable covering layer (e.g. 304a) placed on the powder (see Fig. 3a )) and / or mechanically (partially) strengthened by a suitable process (see Fig. 3 b) ).

[0062] Suitable cover layers include, for example, (polymer) films and / or polymers such as curable epoxy resins, as well as organic and inorganic substances deposited from a gas phase (e.g., CVD). For mechanical consolidation of part or all of the loose powder bed, liquid polymers or organic and inorganic substances deposited from the gas phase (e.g., ALD) can optionally be used. These can penetrate into the spaces between the particles and mechanically bond the particles at their contact points.

[0063] In the following, reference is made to the Figures 4a) and 4b ), which show schematic views of a transmission grating 400a having a substrate 410a thinned back on the back side. In this embodiment, the substrate webs located between the cavities can optionally be completely or partially removed.

[0064] Fig. 4a) shows a transmission grating 400a with a thinned substrate 410a and with a grating structure 420a with first and second grating sections 422a, 424a. The first grating sections 422a are designed in the form of a plurality of particles 430a, as described, for example, previously with reference to Figure 3b ). In other words, Figure 4a ) a transmission grating 400a after re-thinning or partial removal of the remaining rear substrate.

[0065] Figure 4b) shows the transmission grating 400b after performing a further method step according to the invention. Here, the webs of substrate material located between the (partially) solidified particles, i.e., the second grating sections 424b, can be partially removed. The webs of substrate material can be completely or partially removed. Furthermore, the webs of substrate material can be removed from one or both sides of the transmission grating.

[0066] In other words, the Figures 4a) and 4b ) conceivable embodiments in which, after solidification of the loose, dry powder, the remaining substrate on the back is first thinned or partially removed ( Fig. 4a )) and then optionally the intermediate webs are removed, e.g. by means of a suitable etching process, completely or partially from one or both sides (see Fig. 4b)). Thinning the substrate back is optional, but it makes it easier to remove the ridges from the back.

[0067] Through the Figure 4b In the embodiment shown in Figure 1, the contrast between the X-ray-absorbing and the less X-ray-absorbing lines of the grating can be increased. Furthermore, the (partial) removal of the substrate webs allows the grating to be mechanically bent, e.g., to a defined radius. The gaps created by removing the substrate material can optionally be filled with a suitable potting compound with low X-ray absorption (e.g., epoxy resin, PDMS, or other polymers), e.g., to increase mechanical stability.

[0068] A specific approach according to embodiments for the production of X-ray transmission gratings can, for example, involve first creating cavities with a desired grating period in a substrate, e.g., by means of a suitable high-rate etching process. In a further step, an X-ray absorber powder (as an example of a loose powder), such as tungsten or bismuth powder, can be introduced into the cavities in dry form. This can be done, for example, by dosing the dry powder, e.g., together with rubber balls, onto the substrate surface in a special device. The particles can be transported into the cavities and compacted, optionally by superimposing a low-frequency oscillation with ultrasound.

[0069] Figure 5shows a transmission grating 500 produced by means of the inventive method described herein. The transmission grating 500 is filled here, by way of example, with tungsten particles 530. The few tungsten particles (small dots) remaining on the silicon ridges 514 do not interfere with the function of the transmission grating 500. Larger accumulations of tungsten particles 530, however, can be quite disruptive. To avoid such larger accumulations, as previously explained, a sacrificial layer can be used during the production of the transmission grating 500, for example. This sacrificial layer can be applied and structured before the cavities are created, so that before the particles 530 are introduced, the surfaces of the substrate, including the substrate ridges 514, are completely or partially covered by the sacrificial layer.After creating the absorbing grating lines in the substrate, the sacrificial layer can be removed selectively from all other present materials using a suitable etching process. Any remaining unwanted particle accumulations can also be removed accordingly. Alternatively or additionally, the surface of the transmission grating can be ground and / or polished after applying a cover layer to remove absorbing particles 530 outside the X-ray absorbing grating lines from the substrate surface.

[0070] In an optional further process step, the surface of the substrate can be freed of excess powder, e.g. by doctor blade coating. As mentioned above, the loose powder can optionally be fully or partially solidified by means of a coating process. This can be done, for example, using an ALD process with, for example, Al 2 O 3, whereby the previously loose, dry powder can be solidified into solid, porous microstructures. In principle, all mechanically stable layers that can be deposited by means of atomic layer deposition (ALD) are also suitable, such as metals, metal oxides and nitrides as well as polymers and combinations thereof. In other words, embodiments can comprise any such materials as the coating material.

[0071] Below you will find the Figures 6a) to 6h) each show schematic views of individual process steps for producing transmission gratings according to the invention including associated intermediate products.

[0072] Figure 6a ) shows a substrate 610, which can serve as a starting product for a manufacturing method according to the invention. The substrate 610 can comprise silicon, glass, sapphire, ceramic, and / or polymers, or can consist of such a material.

[0073] Figure 6b) shows a process step for creating a lattice structure 601 in or on the substrate 610. In this non-limiting example, the lattice structure 601 may be created by structuring a plurality of cavities 612 into a first main side 611 of the substrate 610. This may be carried out, for example, by etching, e.g., using a high-rate etching process (e.g., reactive ion deep etching). Alternatively or additionally, lithographic processes, e.g., using photoresists, may be used. The cavities 612 may have an aspect ratio, with respect to width / depth, of at least 1:9 or at least 1:5.

[0074] Between the cavities 612, webs 614 can remain. If the cavities 612 are structured directly into the substrate 610, as described above, the webs 614 can accordingly be formed from substrate material that remained during the creation of the cavities 612. In alternative embodiments, these remaining substrate webs 614 can be completely or partially removed and then optionally completely or partially filled with a filler. In this case, the webs 614 arranged between the cavities 612 would completely or partially contain the same filler.

[0075] The cavities 612 are preferably created such that they are arranged periodically in the substrate material. This means that a plurality of cavities 612 can be created, all arranged at the same distance from one another. The grating structure 601 can, for example, have a grating period of less than 50 µm. The thickness of the cavities 612 can be at least 100 µm or more, whereby particularly good absorption of X-rays can be achieved. The thickness is measured in the direction of incidence of the X-rays to be blocked.

[0076] Figure 6c) shows a further process step in which the cavities 612 can be filled with particles 630 in the form of loose, dry powder. The cavities 612 can be filled completely or partially. For this purpose, the dry, loose particle powder 630 can be poured onto a surface of the substrate 610 facing the openings of the cavities 612, or onto the first main side 611 of the substrate 610. Vibrations of a first frequency range (e.g., 25 Hz to 150 Hz) can then be superimposed with vibrations of a second frequency range (e.g., 10 kHz to 100 kHz) in order to transport the dry, loose particles 630 into the cavities 612 and optionally to compact them.

[0077] Subsequently, excess loose particles 630, which may, for example, still be located outside the cavities 612, can be removed so that the filled cavities 612 are at least approximately aligned with the substrate surface.

[0078] Optionally, spherical elements (e.g., rubber balls) can be applied to the substrate surface together with the dry, loose particle powder 630, wherein the spherical elements can have a diameter that is at least three times larger than a maximum width or a maximum diameter of a respective cavity 612. Any agglomerates of the loose, dry particles 630 that may have formed can be broken up by means of the spherical elements. This can be done, in particular, by means of vibrations as explained above, so that the spherical elements move and thereby eliminate inhomogeneities of the loose, dry powder 630 in the cavities 612. The spherical elements are then removed again. Alternatively or additionally, the excess loose particles 630 located on the substrate surface can be removed by means of a doctor blade.

[0079] In general, by using superimposed vibrations and / or spherical elements, but also without applying such optional steps, first lattice sections can be formed which have a largely gas bubble-free and homogeneous distribution of particles 630.

[0080] As explained above, the particles 630 can comprise at least one of the materials tungsten, bismuth, and / or gold or can consist of one of these materials, in powder form in this manufacturing step.

[0081] With reference to Figure 6c) It can therefore be stated up to this point that the transmission grating 600 has a substrate 610 and a grating structure 601. The grating structure 601, in turn, has a plurality of alternately arranged first and second grating sections 621, 622. The first grating sections 621 have a higher absorption for X-ray radiation than the second grating sections 622. The first grating sections 621 can be configured in the form of cavities 612 filled with particles 630. The second grating sections 624 can be configured in the form of webs 614 arranged between the cavities 612. The webs 614 can comprise substrate material and / or a filler.

[0082] In the Figures 6a) to 6h), only two cavities 612 and three webs 614 are shown purely by way of example. However, the transmission grating 600 according to the invention can have significantly more cavities 612 and webs 614, or significantly more alternately arranged first and second grating sections 621, 622. The first grating sections 621, which extend up to the Figure 6c ) process step by means of a dry particle powder 630, can be coated and solidified in optional further process steps, and / or enclosed in the cavities 612 by means of a covering layer. This will be explained below with reference to the Figures 6d) and 6e ) will be explained.

[0083] The Figures 6d) to 6f) show optional further method steps with which a cover layer 640 can be applied to the first main side 611, or to the lattice structure 601 comprising the first and second lattice sections 621, 622. The cover layer 640 can be applied, for example, in the form of a polymer film, a curable polymer layer, or in the form of organic or inorganic substances deposited from the gas phase (e.g., by means of CVD or ALD). The particles 630 can be enclosed in the cavities 612 by means of the cover layer 640.

[0084] As in Figure 6d ), the cover layer 640 can completely span the lattice structure 601. The cover layer 640 can lie on top of the first and second lattice sections 621, 622. This would be the case, for example, with polymer films.

[0085] However, if the cover layer 640 is applied, for example, by means of a coating process, the coating material used, e.g. a liquid polymer, can partially penetrate into the cavities 612, as is shown by way of example in Figure 6e ). It would also be conceivable that the coating material of the cover layer 640 completely penetrates into the cavities 612, as is exemplified in Figure 6f ). The coating material can penetrate the particles 630 located in the cavities 612 and thereby act as a coating for the particles 630.

[0086] Thus, the particle powder 630 located in the cavities 612 can be partially or completely solidified by means of the cover layer 640 or by means of the coating material used. In the case of partial solidification ( Figure 6e)), the particles 630 can form porous bodies 632d, which are arranged in the cavities 612 in the region of the first main side 611 of the substrate. Loose particles 634 that remain uncoated underneath can be enclosed in the cavities 612. The result is a transmission grating 601 with a cover layer 640 that covers the first and second grating sections 621, 622, wherein the first grating sections 621 comprise partially solidified particle powder 630.

[0087] In case of complete penetration ( Figure 6f)) of the particle powder 630 with the coating material, the entire particle powder 630 can be solidified, so that almost all of the particles are solidified into solid porous bodies 632d by the coating. The result is a transmission grating 601 with a cover layer 640 covering the first and second grating sections 621, 622, wherein the first grating sections 621 comprise fully solidified particle powder 630, or solid porous structural bodies 632d.

[0088] Alternatively, the dry particle powder 630, as exemplified in the Figures 6g) and 6h), also independently of a cover layer 640, can be partially or fully solidified by means of a coating 650. For this purpose, for example, a coating process can be used, wherein the particle powder 630 can be solidified into solid porous bodies 632e by means of the coating material used. For the mechanical connection or solidification of the initially loose, dry powder bed 630, for example, liquid polymers or organic or inorganic substances deposited from the gas phase (e.g., by means of ALD / CVD) can be used. These penetrate into the spaces between the individual particles and connect the particles to one another at their respective contact points.

[0089] In summary, the first lattice sections 621 of the lattice structure 601 can be formed by means of particles located in the cavities 612, which particles are either present only in the form of a loose, dry powder 630 and can optionally be enclosed in the cavities 612 with a cover layer 640 to secure them against falling out. Alternatively or additionally, the particle powder 630 can be partially solidified, wherein a mixture of solid porous bodies 632d, 632e and unsolidified, i.e. loose, dry powder 630 is present, wherein this mixture forms the first lattice sections 621. Here, too, a cover layer 640 can optionally be present. Alternatively, the particle powder 630 can be fully solidified, wherein solid porous bodies 632d, 632e are present, which then in turn form the first lattice sections 621. Here, too, a cover layer 640 can optionally be present.

[0090] In the method steps described above, the first lattice sections 621 were created by structuring cavities 612 in the substrate 610, which were then filled with dry particle powder 630, wherein the particle powder 630 was (partially) solidified. The second lattice sections 622 were in the form of webs 614 made of substrate material that remained during the structuring of the substrate. The method according to the invention can optionally comprise further method steps. For example, the webs 614 made of substrate material can be completely or partially removed. The removed regions can then be filled, likewise completely or partially, with a filler. In this case, webs 614 are created from filler.

[0091] The Figures 7a) to 7t) show different possibilities of how a transmission grating 700 with first and second grating sections 721, 722 can be produced by means of the method according to the invention. In all Figures 7a) to 7t ) transmission gratings are designated by 700, first grating sections by 721, second grating sections by 722, substrates by 710, webs by 714, particles by 730, cover layers by 740 and fillers or potting materials by 750. In comparison to the Figures 6a) to 6h ) The particles 730 are shown here in a simplified form. However, the particles 730 can also be in the form of loose, dry powders or in the form of solid porous bodies, which can be produced from particles partially or fully solidified by means of a coating.

[0092] Fig. 7a ) first shows an embodiment as previously described with reference to the Figures 6d) to 6f ). Optionally, the substrate 710 can be thinned from a rear side ( Figure 7b )). Furthermore, the webs 714 made of substrate material arranged between the first grid sections 721 can optionally be at least partially removed ( Figure 7c )). Alternatively, the webs 714 can also be removed completely, see Fig. 7 d) The removal of the webs 714 can occur from a rear side, as shown by way of example in the figures. Alternatively or additionally, the webs 714 can also be completely or partially removed from a front side of the substrate 710. In these cases, the second grid sections 722 can be formed in the form of air gaps between the first grid sections 721 (e.g., (partially solidified) particles).

[0093] As in the Figures 7e) and 7f), the removed substrate regions can optionally be completely or partially filled again using a filler 750, e.g., with a potting compound. In this case, the second lattice sections 722 can be formed in the form of webs 714 made of filler material and / or substrate material between the first lattice sections 721 (e.g., (partially solidified) particles).

[0094] Figure 7g ) shows an embodiment without a cover layer. Here, too, the substrate 710 can optionally be thinned from a rear side ( Figure 7h )). Furthermore, webs 714 made of substrate material can be formed entirely ( Figure 7j )) or partially ( Figure 7i )) can be removed. In both cases, the substrate 710 can also be thinned on the back ( Figure 7k )). Optionally, the removal of the webs 714 from substrate material can also be carried out from the back of the substrate 710, ie opposite the first main side 711 ( Figure 7l )). Alternatively, the removal of the webs 714 made of substrate material can also be carried out starting from both sides of the substrate 710, wherein, due to an incomplete removal, a section 715 made of substrate material can optionally remain ( Figures 7m) and 7n )).

[0095] In these cases, removed substrate material can also be filled with a filler 750 ( Figures 7o) to 7t Depending on whether the areas of removed substrate material are completely or partially filled with the filler 750, the second lattice sections 722 may comprise the filler 750 and / or substrate material. In all cases where filler 750 is used, this filler 750 may have a lower absorption for X-rays than the particles 730.

[0096] As in the Figures 7a) to 7t), the first lattice sections 721 formed by means of the particles 730 can also be arranged only partially in a cavity in the substrate 710. The cavities can be formed by means of substrate material or also by means of the filler 750, wherein the first lattice sections 721 can thus be arranged partially in cavities formed by means of substrate material and partially in cavities formed by means of filler 750.

[0097] As in the Figures 7a) to 7t ), the second grating sections 721 can be formed by means of substrate material, by means of substrate material and filler 750, or only by means of filler 750, so that they are each arranged alternately with the first grating sections 721 to form the transmission grating 700.

[0098] At this point, it should be emphasized again that the exemplary embodiments generally provide particularly cost-effective production compared to existing processes. Furthermore, a particularly homogeneous filling can optionally be achieved, particularly by avoiding gas bubble inclusions. Furthermore, a wide variety of materials can be used, with tungsten being a particularly advantageous absorber material.

[0099] As previously explained in detail, some embodiments allow for dry filling of dry, loose particles into cavities, thus avoiding gas bubble inclusions, such as those that occur during wet filling. This allows for the creation of particularly homogeneous structures.

[0100] In addition to the high flexibility in material selection, embodiments also enable the realization of very short processing times. Furthermore, high aspect ratios (e.g., of the cavities and thus of the first grating sections) can be achieved. In particular, absorber materials can be used independently, or essentially independently, of their melting point (e.g., with respect to a melting point of the substrate material). The inventive use of coating processes enables, in particular, a "gentle" processing of the transmission grating with respect to thermal stress (e.g., by performing the coating at moderate temperatures), so that even thermally sensitive materials can be used.

[0101] Furthermore, according to embodiments, electroplating can be dispensed with. Thus, as explained above, embodiments can, in particular, comprise tungsten particles.

[0102] The transmission gratings according to the invention can be used, for example, in dark-field radiography (e.g., non-destructive analysis, clinical application) and / or in dark-field computed tomography (e.g., non-destructive analysis, clinical application).

[0103] All lists of materials, environmental influences, electrical properties and optical properties listed herein are to be considered exemplary and not exhaustive.

[0104] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

[0105] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

[0106] In the following, embodiments according to the present invention are summarized again: A first embodiment comprises a method for producing a microstructured transmission grating (100, 300a,b, 400a,b) for X-radiation, the method comprising the following steps: providing a substrate (110, 210, 310a,b, 410a,b, 610, 710) and producing a grating structure (120, 320a,b, 420a,b) by structuring a plurality of periodically arranged cavities (112, 212, 612) in a first main side of the substrate, wherein individual webs (114, 514, 614) made of substrate material remain between the cavities; Filling the cavities with particles (130, 230, 330a,b, 430a,b, 530, 630, 730) in the form of loose, dry powder; wherein the substrate has a lower absorption for X-ray radiation than the particles located in the cavities.

[0107] According to a second embodiment, the method according to the first embodiment further comprises: at least partially solidifying the particles located within the cavities (112, 212, 612) using a coating process to provide at least a portion of the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) in the form of a plurality of solidified porous bodies (632d,e) with higher X-ray absorption compared to the substrate (110, 210, 310a,b, 410a,b, 610, 710).

[0108] According to a third embodiment, in the method according to the second embodiment, the particles located in the individual cavities (112, 212, 612) are each completely solidified into porous bodies (632 d, e) by means of the coating process.

[0109] According to a fourth embodiment, in the method according to the second or third embodiment, the coating process is carried out using a liquid polymer; and / or the coating process comprises a deposition of organic or inorganic substances from a gas phase, e.g., by means of chemical vapor deposition or e.g., by means of atomic layer deposition.

[0110] According to a fifth embodiment, the method according to one of the previous embodiments further comprises: applying a cover layer (340a, 640, 740) to the first main side of the substrate in order to enclose the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) located in the cavities (112, 212, 612) therein.

[0111] According to a sixth embodiment, in the method according to the fifth embodiment, the application of the cover layer (340a, 640, 740) comprises at least one of the following steps: Application of a mechanically stable film, e.g. a polymer film or a metal film, application of a polymer layer, and / or application of organic or inorganic substances deposited from the gas phase, e.g. by means of chemical and / or physical gas phase deposition or e.g. by means of atomic layer deposition.

[0112] According to a seventh embodiment, the method according to one of the previous embodiments further comprises: re-thinning a second main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) opposite the first main side of the substrate.

[0113] According to an eighth embodiment, the method according to one of the previous embodiments further comprises: at least partially removing one or more of the remaining webs (114, 514, 614) made of substrate material.

[0114] According to a ninth embodiment, in the method according to the eighth embodiment, the webs (114, 514, 614) are at least partially removed starting from the first main side, and / or the webs are at least partially removed starting from a second main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) opposite the first main side.

[0115] According to a tenth embodiment, the method according to the eighth or ninth embodiment further comprises: at least partially filling the regions in which the webs (114, 514, 614), or parts of the webs, were removed from substrate material with a filler (750); wherein the filler has a lower absorption for X-ray radiation than the particles (130, 230, 330a,b, 430a,b, 530, 630, 730).

[0116] According to an eleventh embodiment, the method according to one of the previous embodiments further comprises: applying a sacrificial layer to the first main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) before producing the lattice structure (120, 320a,b, 420a,b); wherein the structuring of the plurality of periodically arranged cavities (112, 212, 612) in the first main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) comprises structuring the sacrificial layer such that the individual webs (114, 514, 614) remaining between the cavities (112, 212, 612) remain covered by the sacrificial layer; and wherein the method further comprises removing the sacrificial layer after filling the cavities (112, 212, 612) with the particles (130, 230, 330a,b, 430a,b, 530, 630, 730).

[0117] A twelfth embodiment comprises a microstructured transmission grating (100, 300a,b, 400a,b) for X-ray radiation, wherein the transmission grating has the following features: a substrate (110, 210, 310a,b, 410a,b, 610, 710) with a grating structure (120, 320a,b, 420a,b), wherein the grating structure has a plurality of alternately arranged first and second grating sections; wherein the first grating sections (122, 322a,b, 422a,b) have a plurality of particles (130, 230, 330a,b, 430a,b, 530, 630, 730) which are in the form of loose, dry powder and / or in the form of particles solidified by means of a coating; and wherein the first grating sections have a higher absorption for X-ray radiation than the second grating sections, so as to form the microstructured transmission grating for the X-ray radiation.

[0118] According to a thirteenth embodiment, in the transmission grating according to the twelfth embodiment, the substrate (110, 210, 310a,b, 410a,b, 610, 710) has a plurality of periodically arranged cavities (112, 212, 612); and the respective cavities form the first grating sections (122, 322a,b, 422a,b).

[0119] According to a fourteenth embodiment, in the transmission grating according to the thirteenth embodiment, a respective cavity (112, 212, 612) has an aspect ratio, with respect to width to depth, of at least 1:9 or of at least 1:5.

[0120] According to a fifteenth embodiment, in the transmission grating according to the thirteenth or fourteenth embodiment, the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) are present both in the form of loose, dry powder and in the form of particles solidified into porous bodies (632d,e) by means of a coating; and the loose, dry powder is enclosed in the cavities (112, 212, 612) between the solidified particles and the substrate (110, 210, 310a,b, 410a,b, 610, 710).

[0121] According to a sixteenth embodiment, in the transmission grating according to the twelfth, thirteenth or fourteenth embodiment, the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) are in the form of particles completely solidified into porous bodies (632d,e) by means of a coating, wherein the porous bodies each form the first grating sections (122, 322a,b, 422a,b).

[0122] According to a seventeenth embodiment, in the transmission grating according to the fifteenth or sixteenth embodiment, the first grating sections (122, 322a,b, 422a,b) have a defect-free distribution of particles (130, 230, 330a,b, 430a,b, 530, 630, 730), wherein defects are cavities that are several times larger than an average pore size of the porous bodies (632d,e).

[0123] According to an eighteenth embodiment, in the transmission grating according to one of the twelfth to seventeenth embodiments, the second grating sections comprise substrate material and / or a material different from the substrate (110, 210, 310a,b, 410a,b, 610, 710), wherein the material different from the substrate (110, 210, 310a,b, 410a,b, 610, 710) is configured in the form of a filler (750) with a lower X-ray absorption compared to the first grating sections (122, 322a,b, 422a,b).

[0124] According to a nineteenth embodiment, the transmission grating according to any one of the twelfth to eighteenth embodiments further comprises: a cover layer (340a, 640, 740) arranged on the grating structure (120, 320a,b, 420a,b) in order to enclose the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) in the first grating sections (122, 322a,b, 422a,b).

[0125] According to a twentieth embodiment, in the transmission grating according to one of the twelfth to nineteenth embodiments, a grating period of the grating structure (120, 320a,b, 420a,b) is less than 50 µm.

[0126] According to a twenty-first embodiment, in the transmission grating according to one of the twelfth to twentieth embodiments, the first grating sections (122, 322a,b, 422a,b) each have a thickness of at least 100 µm, to be measured in the direction of incidence of the X-radiation.

[0127] According to a twenty-second embodiment, in the transmission grating according to any one of the twelfth to twenty-first embodiments, the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) contain tungsten or consist of tungsten.

[0128] According to a twenty-third embodiment, in the transmission grating according to one of the twelfth to twenty-second embodiments, the substrate (110, 210, 310a,b, 410a,b, 610, 710) comprises or consists of at least one of the following materials: silicon, glass, sapphire, ceramic, or polymers. References

[0129] [1] C. Kostmann, T. Lisec, M. Bodduluri, and 0. Andersen, "Automated Filling of Dry Micron-Sized Particles into Micro Mold Pattern within Planar Substrates for the Fabrication of Powder-Based 3D Microstructures," Micromachines, vol. 12, no. 10, p. 1176, 2021, doi: 10.3390 / mi12101176. [2] T. Lisec, 0. Behrmann, and B. Gojdka, "PowderMEMS-A Generic Microfabrication Technology for Integrated Three-Dimensional Functional Microstructures," Micromachines, vol. 13, no. 3, p. 398, 2022, doi:10.3390 / mi 13030398.

Claims

1. A method for producing a microstructured transmission grating (100, 300a,b, 400a,b) for X-rays, the method comprising the following steps: providing a substrate (110, 210, 310a,b, 410a,b, 610, 710) and creating a grating structure (120, 320a,b, 420a,b) by structuring a plurality of periodically arranged cavities (112, 212, 612) in a first main side of the substrate, wherein individual webs (114, 514, 614) made of substrate material remain between the cavities; filling the cavities with particles (130, 230, 330a,b, 430a,b, 530, 630, 730) in the form of loose, dry powder; wherein the substrate has a lower absorption for X-rays than the particles in the cavities.

2. The method of claim 1, further comprising: at least partially solidifying the particles located within the cavities (112, 212, 612) using a coating process to provide at least a portion of the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) in the form of a plurality of solidified porous bodies (632d,e) with higher X-ray absorption compared to the substrate (110, 210, 310a,b, 410a,b, 610, 710).

3. The method according to claim 2, wherein the coating process is carried out using a liquid polymer; and / or wherein the coating process comprises deposition of organic or inorganic substances from a gas phase, e.g., by means of chemical vapor deposition or e.g., by means of atomic layer deposition.

4. The method according to any one of the preceding claims, further comprising: re-thinning a second main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) opposite the first main side of the substrate.

5. The method according to any one of the preceding claims, further comprising: at least partially removing one or more of the remaining webs (114, 514, 614) of substrate material, and at least partially filling the regions in which the webs (114, 514, 614), or parts of the webs, were removed from substrate material with a filler (750); wherein the filler has a lower absorption for X-ray radiation than the particles (130, 230, 330a,b, 430a,b, 530, 630, 730).

6. The method according to any one of the preceding claims, further comprising: applying a sacrificial layer to the first main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) prior to creating the lattice structure (120, 320a,b, 420a,b); wherein structuring the plurality of periodically arranged cavities (112, 212, 612) in the first main side of the substrate (110, 210, 310a,b, 410a,b, 610, 710) comprises structuring the sacrificial layer such that the individual webs (114, 514, 614) remaining between the cavities (112, 212, 612) remain covered by the sacrificial layer; and wherein the method further comprises removing the sacrificial layer after filling the cavities (112, 212, 612) with the particles (130, 230, 330a,b, 430a,b, 530, 630, 730).

7. A microstructured transmission grating (100, 300a,b, 400a,b) for X-rays, the transmission grating having the following features: a substrate (110, 210, 310a,b, 410a,b, 610, 710) with a grating structure (120, 320a,b, 420a,b), the grating structure having a plurality of alternately arranged first and second grating sections; the first grating sections (122, 322a,b, 422a,b) having a plurality of particles (130, 230, 330a,b, 430a,b, 530, 630, 730) which are in the form of loose, dry powder and / or in the form of particles solidified by means of a coating; and wherein the first grating sections have a higher absorption for X-ray radiation than the second grating sections, so as to form the microstructured transmission grating for the X-ray radiation.

8. The transmission grating (100, 300a,b, 400a,b) according to claim 7, wherein the substrate (110, 210, 310a,b, 410a,b, 610, 710) has a plurality of periodically arranged cavities (112, 212, 612); and wherein the respective cavities form the first grating sections (122, 322a,b, 422a,b).

9. The transmission grating (100, 300a,b, 400a,b) according to claim 8, wherein the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) are present both in the form of loose, dry powder and in the form of particles solidified into porous bodies (632d,e) by means of a coating; and wherein the loose, dry powder is enclosed between the solidified particles and the substrate (110, 210, 310a,b, 410a,b, 610, 710) in the cavities (112, 212, 612).

10. Transmission grating (100, 300a,b, 400a,b) according to one of claims 7 to 8, wherein the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) are in the form of particles completely solidified into porous bodies (632d,e) by means of a coating, wherein the porous bodies each form the first grating sections (122, 322a,b, 422a,b).

11. Transmission grating (100, 300a,b, 400a,b) according to one of claims 9 or 10, wherein the first grating sections (122, 322a,b, 422a,b) have a defect-free distribution of particles (130, 230, 330a,b, 430a,b, 530, 630, 730), wherein defects are cavities that are several times larger than an average pore size of the porous bodies (632d,e).

12. Transmission grating (100, 300a,b, 400a,b) according to one of claims 7 to 11, wherein the second grating sections comprise substrate material and / or a material different from the substrate (110, 210, 310a,b, 410a,b, 610, 710), wherein the material different from the substrate (110, 210, 310a,b, 410a,b, 610, 710) is designed in the form of a filler (750) with a lower X-ray absorption compared to the first grating sections (122, 322a,b, 422a,b).

13. Transmission grating (100, 300a,b, 400a,b) according to one of claims 7 to 12, further comprising: a cover layer (340a, 640, 740) arranged on the grating structure (120, 320a,b, 420a,b) to enclose the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) in the first grating sections (122, 322a,b, 422a,b).

14. The transmission grating (100, 300a,b, 400a,b) according to any one of claims 7 to 13, wherein a grating period of the grating structure (120, 320a,b, 420a,b) is less than 50 µm; and / or wherein the first grating sections (122, 322a,b, 422a,b) each have a thickness of at least 100 µm, measured in the direction of incidence of the X-ray radiation.

15. Transmission grating (100, 300a,b, 400a,b) according to one of claims 7 to 14, wherein the particles (130, 230, 330a,b, 430a,b, 530, 630, 730) contain tungsten or consist of tungsten.

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