METHOD FOR PRODUCE A MICROSTRUCTURED DEVICE FILLED WITH LOOSE POWDER PARTICLES

Abstract

A method for manufacturing a microstructured device (100) filled with loose powder particles (140) is disclosed. A molded body (110) is provided with a first and a second fluid opening (121, 122) and a cavity (123) arranged between them. The second fluid opening (122) is closed by means of a temporary closure device (130). The cavity (123) is filled with loose powder (140). The powder particles located in the region of the first fluid opening (121) are coated and agglomerated to form a rigid, porous structure (141) which permanently closes the first fluid opening (121). After the temporary closure device (130) is removed, the powder particles located in the area of ​​the second fluid opening (122) are coated and agglomerated into a rigid, porous structure (142) which permanently closes the second fluid opening (122).Uncoated powder particles (140) are permanently enclosed in the cavity (123) by means of the porous structures (141, 142) that close the respective fluid openings (121, 122).

Description

[0001] The innovative concept described here lies in the technical field of microstructuring, which can be used to produce devices with dimensions in the micrometer or nanometer range. Examples of these are so-called MEMS components (MEMS: Micro Electro Mechanical System).

[0002] The publication "LISEC, Thomas; BEHRMANN, Ole; GOJDKA, Björn. PowderMEMS - A generic microfabrication technology for integrated three-dimensional functional microstructures. in Micromachines, 2022, Vol. 13, No. 3, p. 398" describes a process known as PowderMEMS. Here, micrometer-sized particles are solidified by atomic layer deposition to create porous three-dimensional microstructures on planar substrates.

[0003] EP 3 363 533 A1 describes a device comprising a substrate having a recess and a plurality of particles arranged in the recess. A first portion of the particles is bonded to a porous structure by means of a coating. A second portion of the particles is not bonded by means of the coating. The first portion of particles is arranged closer to an opening of the recess than the second portion of particles, thus preventing the second portion of particles from escaping from the recess through the opening.

[0004] DE 10 2016 215 617 A1 describes a method for producing a device, wherein a substrate is provided which has a recess. A plurality of loose particles is introduced into the recess. A first portion of the particles is coated using a coating process which has a penetration depth starting from an opening of the recess along a depth direction into the recess, so that the first portion is bonded to form a solidified porous structure. The penetration depth of the coating process into the recess is adjusted such that a second portion of the particles is not bonded by means of the coating, and such that the solidified first portion of the particles is arranged between the second portion of the particles and an area surrounding the recess. According to the invention, the second portion of the particles is at least partially removed from the recess.

[0005] DE 10 2011 010 899 A1 describes a method for producing a three-dimensional structure. The method involves applying or introducing particles onto or into a carrier element, wherein a plurality of at least partially interconnected cavities are formed between the particles, and wherein the particles come into contact with each other at contact points. The particles are connected at the contact points by coating the arrangement of particles and carrier element, wherein the cavities are at least partially penetrated by the layer created during the coating process.

[0006] The present disclosure presents an innovative method for producing microstructured devices containing loose powder particles. In preferred embodiments, these powder particles may contain an active material.

[0007] A wide variety of sensors and devices are based on the interaction of sorbent, chemically or catalytically active materials with gases or liquids. During sorption, ions, atoms, or molecules of other substances are enriched in the volume of the sorbent (absorption) or on its surface (adsorption). Absorbent materials are used, for example, in exhaust gas purification and water treatment plants or air filters to remove toxic substances. Adsorbents are widely used, for example, in chromatographic columns for substance separation or in gas detection systems for the enrichment of substances that must be detected in extremely low concentrations. Getter materials, which are used to maintain a vacuum in a closed volume, can be based either on sorption or on a chemical reaction with the gas to be bound. Catalysts accelerate chemical reactions on a surface on which they are located.

[0008] All of these materials are also of great interest for microsystems (MEMS), e.g., for the production of miniaturized filters. Active filters for removing pollutants from air and water are generally based on chemically or catalytically active or sorbent materials with a large internal surface area that are embedded in a permeable volume. It is often advantageous to use loose powder, as otherwise the activity of the respective material can be impaired during further processing, e.g., into pellets or suspensions. To prevent the powder from falling out of the permeable volume, the inlet and outlet are sealed, e.g., using glass wool, filter paper, or microporous film.

[0009] Such systems are currently only available in relatively large dimensions, making them unsuitable for use at the system level in microstructuring. However, active filters made of loose powder material would also be of interest for miniaturized systems, microsystems, or MEMS. However, it has simply not been possible to realize them using MEMS manufacturing techniques. The present invention discloses a suitable, mass-producible process for this purpose.

[0010] This object is achieved by the method according to the invention and by a microstructured device filled with loose powder particles according to the independent claims, which can be produced using this method.

[0011] Further embodiments and advantageous aspects of this method and the corresponding device are mentioned in the respective dependent patent claims.

[0012] Some exemplary embodiments are shown in the drawing and explained below. They show: Fig. 1A-1E are schematic side sectional views of a microstructured device that can be manufactured using the method according to the invention, Fig. 2A-2H are schematic side sectional views of a microstructured device that can be manufactured using the method according to the invention, and Fig. 3A-3D are schematic side sectional views of a microstructured device that can be manufactured using an alternative variant of the method according to the invention.

[0013] In the following, embodiments are described in more detail with reference to the figures, wherein elements with the same or similar function are provided with the same reference numerals.

[0014] Method steps depicted or described within the scope of the present disclosure may also be performed in a different order than that depicted or described. Furthermore, method steps relating to a specific feature of a device are interchangeable with that same feature of the device, and the same applies vice versa.

[0015] The following examples refer to uncoated loose powder particles with sorbing and / or catalytic properties. Adsorption includes, among other things, physical adsorption, also referred to as physisorption, and chemical adsorption, also referred to as chemisorption. Chemisorption is a fundamental process in catalysis with solid catalysts, which is why, in the context of the present disclosure, catalysis, and in particular heterogeneous catalysis, also falls under the term adsorption. Accordingly, the terms "sorbing property" and "catalytic property" used herein can be used synonymously. If, for example, sorption particles are mentioned in the context of this disclosure, these sorption particles can have sorbing and / or catalytic properties.

[0016] The microstructured device according to the invention falls within the field of MEMS technology. In MEMS technology, it is known that all components present on a planar substrate (e.g., made of silicon or glass) can be processed in parallel. Using known methods, it is quite possible to fill microcavities in a substrate with powder simultaneously, e.g., manually by doctor blade coating (doctor blade method) or by a mechanical procedure. However, creating a permeable seal at the substrate level has long been a problem.

[0017] To realize such devices with fluid-permeable closures, only the housing was prefabricated at the substrate level and separated into components. The individual components were then serially filled with powder and sealed. In conventional processes, the powder is manually introduced into a cavity in a lower silicon chip, which is then closed with an upper silicon chip of the appropriate size. The cross-section of the fluidic openings in the upper silicon chip is sufficiently small to prevent the coarse-grained powder from falling out. In other known processes, a copper housing, completely prefabricated at the substrate level, is filled with powder through its fluidic connections. One connection is secured with a metal sieve before filling. The other connection is closed with glass wool after filling.

[0018] However, these known methods at the component level are too complex and therefore far too expensive for cost-effective mass production. A further disadvantage of these designs is that the fluidic connections are always located only on the top side of the component. Advantageously, however, such devices, such as pre-concentrators, should be flowed through by a fluid stream with as little resistance as possible and without abrupt changes in direction. This can be achieved with the method and device according to the invention.

[0019] The Fig. 1A to 1E objectively show an embodiment of a method according to the invention for producing a microstructured device 100 filled with loose powder particles.

[0020] As in Fig. As can be seen in Figure 1A, a microstructured molded body 110 can first be provided. In the non-limiting embodiment shown here, the molded body 110 can be configured in the form of a planar substrate. This can be, for example, a semiconductor or glass substrate. In principle, however, the molded body 110 can have any geometric shape and any material. The molded body 110 can have dimensions in the millimeter to micrometer range and can be structured using MEMS techniques.

[0021] According to the invention, the molded body 110 has at least one first fluid opening 121 and at least one second fluid opening 122 arranged opposite one another, with a cavity 123 located between the two fluid openings 121, 122. As shown in this exemplary embodiment, the molded body 110 can have one or more first fluid openings 121 and one or more second fluid openings 122, each with a cavity 123 arranged therebetween. For the sake of simplicity, however, the invention will be described below using only the example of a single first fluid opening 121 and a single second fluid opening 122 with a single cavity 123 arranged therebetween. However, the description naturally also applies to all other fluid openings 121, 122 and cavities 123.

[0022] The fluid openings 121, 122, together with the cavity 123 located therebetween, can be configured, for example, in the form of a through-hole extending from a first surface (top side) 111 of the molded body 110 to an opposite second surface (bottom side) 112 of the molded body 110. Such a through-hole 121, 122, 123 can extend straight through the molded body 110. For example, such a through-hole can be created using an etching process, e.g., DRIE (Deep Reactive Ion Etching). According to embodiments, the first and second fluid openings 121, 122 and the cavity 123 can each have a diameter of less than 2 mm or less than 1 mm.

[0023] Fig. 1B shows a further method step in which the second fluid opening 122 is closed by means of a temporary closure device 130. The temporary closure device 130 can be attached to the molded body 110 in the form of a detachable connection. The opposite first fluid opening 121, however, can remain open and accessible.

[0024] The temporary or releasable closure device 130 for temporarily or releasably closing the second fluid opening 122 can, for example, be designed in the form of a film that is removably laminated to the molded body 110. However, it would also be conceivable for it to be a type of lid that is releasably attached to the molded body 110, e.g., by means of a clamp.

[0025] Fig. 1C shows a further method step. As can be seen here, the cavity 123 can first be filled with a loose, dry powder 140. The loose, dry powder 140 can be introduced through the openly accessible first fluid opening 121. The loose, dry powder 140 can trickle into the cavity 123 due to gravity and fall downward until it reaches the temporary closure device 130. The cavity 123 can preferably be completely filled with the loose, dry powder 140, so that the introduced powder 140 completely fills the cavity 123. The dry powder 140 used here differs from wet powders dissolved in suspensions.

[0026] Furthermore, in Fig. 1C shows that, in a subsequent process step, the loose powder particles located in the region of the first fluid opening 121 can be solidified. Such solidification of loose powder particles can be carried out, for example, using a coating method, e.g., an ALD coating process (ALD: Atomic Layer Deposition). The powder particles solidified by the coating material can form a rigid, porous structure 141 that permanently closes the first fluid opening 121.

[0027] This rigid, porous structure 141 can be highly rigid and simultaneously permeable to fluids, allowing, for example, gases and / or liquids to pass through or flow through the rigid, porous structure 141. This allows gases and / or liquids to penetrate the cavity 123, even though it is tightly sealed from the outside by the rigid, porous structure 141. The rigid, porous structure 141 can thus be configured in the form of a rigid, porous membrane.

[0028] In general, the rigid, porous structure 141 can be described as a micro-molded body that permanently seals the first fluid opening 121. Permanent sealing means that the rigid, porous structure 141 cannot be removed non-destructively. This is due, among other things, to the fact that the coated particles adhere to the inside of the first fluid opening 121. This means that, on the one hand, the previously loose powder particles 140 are coated by means of the coating material and solidified to form the rigid, porous structure 141. On the other hand, the coating material ensures that the rigid, porous structure 141 adheres to the inner walls of the through-hole 121, 122, 123. Since the coating material forms only a very thin layer, the pores between the particles contained in the loose, dry powder 140 are largely preserved, so that liquids or gases can easily flow through the porous structure 141.

[0029] As mentioned above, only those particles of the loose powder 140 located in the region of the first fluid opening 121 are solidified. This means that the coating does not completely penetrate the cavity 123 and thus does not solidify all of the loose powder particles 140 located in the cavity 123. In the case of an ALD coating, the penetration depth of the coating material can be precisely adjusted, for example, based on the process parameters. For example, the penetration depth can be varied by the amount and residence time of the precursors in the reactor.

[0030] The thickness of the rigid, porous structure 140 is therefore determined, among other things, by the penetration depth of the coating material deposited during atomic layer deposition. According to embodiments, the atomic layer deposition can be carried out such that the penetration depth of the deposited coating material is less than 30% or less than 10% of the total height of the powder particles 140 located in the cavity 123. This means that less than 30% or less than 10% of the powder particles 140 located in the cavity 123 are coated and thereby solidified into the rigid, porous structure 141.

[0031] In general, the particles of the loose powder 140 to be coated should preferably be as small and irregularly shaped as possible (e.g., gravel-like) in order to achieve a particularly robust or solid porous structure 141. According to embodiments, the uncoated powder particles 140 enclosed in the cavity 123 can have an average particle size of 1 µm to 25 µm. The average particle size corresponds to the mean particle diameter, also referred to as D50.

[0032] At the same time, the rigid, porous structure 141 should have a defined thickness, i.e., the ALD layer should not penetrate to any desired depth, so that a large portion (e.g., over 50%) of the loose powder particles 140 located within the cavity 123 remain essentially uncoated. For this purpose, the powder particles to be coated should also be as small as possible, since in this case, the cavities between individual particles, through which the ALD precursors penetrate into the powder bed, are also small, while simultaneously providing a large surface area.

[0033] Fig. 1D shows a further method step. Here, the molded body 110 was first turned over so that the previously upper first surface 111 of the molded body 110 is now directed downwards and now forms the underside, while the previously lower second surface 112 is now directed upwards and forms the upper side. The terms "bottom" and "top" are to be understood in the usual sense, with loose powder 140 falling from top to bottom due to gravity. After the molded body 110 has been turned over, the temporary closure device 130 closing the first fluid opening 121 can be removed again so that the second fluid opening 122 is now openly accessible again, and so that the loose powder particles 140 located in the region of the second fluid opening 122 are exposed again.

[0034] As in Fig. 1D, the rigid, porous structure 141 is now located on the underside of the molded body 110. By means of the rigid, porous structure 141, the uncoated loose powder 140 located in the cavity 123 can be secured against falling out due to gravity. Optionally, however, it would also be conceivable that, in addition to the rigid, porous structure 141, a temporary closure device (not shown here) is attached to the first surface 111 of the molded body 110. Such a temporary closure device can protect the already coated particles of the rigid, porous structure 141 from further coating in the next step ( Fig. 1E). If a second coating of the rigid, porous structure 141 is not critical, the optional temporary closure device can also be omitted. In any case, such a temporary closure device (closing the first fluid opening 121) can have essentially the same structure and the same properties as the previously described temporary closure device 130 for closing the first fluid opening 121.

[0035] Fig. 1E shows a further method step. Here, the loose powder particles 140 located in the region of the second fluid opening 122 can now also be solidified using a coating process, such as an ALD coating process. Here, too, the powder particles 140 solidified by means of the coating material form a rigid, porous structure 142. This structure, like the rigid, porous structure 141 arranged in the region of the first fluid opening 121, can have a membrane function. Here, too, the second fluid opening 122 is permanently closed by means of the rigid, porous structure 142. The penetration depth can also be adjusted, as previously described, so that less than 30% or less than 10% of the loose particles 140 are solidified into the rigid, porous structure 142.

[0036] If a temporary closure device described above for closing the first fluid opening 121 has previously been applied to the first surface 111 of the molded body 110, this can be removed again after the rigid, porous structure 142 has been created.

[0037] In summary, it can be stated that, for example, a substrate 110 with through-holes 121, 122, 123 can initially be reversibly sealed on one side. After the introduction of loose powder 140, this can be solidified to a defined depth into a porous micro-molded body 141. This micro-molded body 141 mechanically fixes the loose powder 140 remaining underneath in the through-hole 121, 122, 123. The substrate 110 can then be turned over, and the temporary closure 130 can be removed. The loose powder 140 can then be solidified again to a defined depth, so that the remaining loose powder 140 is subsequently mechanically fixed on both sides in the through-hole 121, 122, 123.

[0038] By means of the method according to the invention, both the first and second fluid openings 121, 122 can be closed by means of a rigid, porous structure 141, 142. Uncoated powder particles 140 within the cavity 123 are thus permanently enclosed in the cavity 123 by means of the porous structures 141, 142 closing the respective fluid openings 121, 122. This leaves a molded body 110, e.g., in the form of a substrate with through-openings, which contains a filling of loose powder 140, wherein the loose powder 140 is held in place by two mechanically strong, porous membranes 141, 142.

[0039] The Fig. 2A to 2H show a further embodiment of a method according to the invention. Elements with the same or similar function are identified by the same reference numerals as in the Fig. 1A to 1E. Therefore, the differences from the previously discussed embodiment will be discussed in more detail below.

[0040] As initially in the Fig. 2A to 2C, a molded body 110, e.g., in the form of a planar substrate, is provided. The molded body 110 has one or more first fluid openings 121 on its first surface 111. On its second surface 112 opposite the first surface 111, the molded body 110 has one or more second fluid openings 122. Between each first and a second fluid opening 121, 122 there is a cavity 123. In the non-limiting embodiment shown here, the molded body 110 is configured in the form of a silicon substrate. The silicon substrate 110 has one or more through-holes 121, 122, 123, which have been produced using a suitable etching process.

[0041] The second surface 112 of the substrate 110 is closed with a temporary closure device 130 so that the second fluid openings 122 are covered or closed ( Fig. 2B). For example, a film 130 can be laminated onto the first surface 111 of the substrate 110. Subsequently ( Fig. 2C), loose dry powder 140 is filled into the cavities 123 from above, ie through the first fluid openings 121, whereby the powder 140 trickles into the cavities 123 due to gravity.

[0042] As in Fig. As can be seen in Figure 2D, the first surface 111 of the substrate 110 is coated, e.g., using an ALD process. The coating material 150 used in this process adheres to the loose powder particles 140 located in the region of the first fluid opening 121 and solidifies (agglomerates) them into a rigid, porous structure 141. The ALD layer 150 can also be deposited on the first surface 111 of the substrate 110, although this is not critical.

[0043] Fig. 2E shows a further method step, wherein the substrate 110 is first turned over so that the first surface 111 of the substrate 110 now forms the underside, and the second surface 112 of the substrate 110 now forms the top side. Optionally, a second temporary closure device 131, e.g., in the form of a film, can be arranged (e.g., laminated) on the first surface 111. The second temporary closure device 131 covers or closes the first fluid openings 121 and the rigid, porous structures 141 formed therein.

[0044] As in Fig. 2F, the first temporary closure device 130 can then be removed from the second surface 112 of the substrate 110, so that the second fluid openings 122 and the powder 140 located in the cavities 123 are again freely accessible.

[0045] Afterward ( Fig. 2G), the loose powder particles 140 located in the region of the second fluid openings 122 can be coated again, e.g., by means of an ALD coating 150. The coating material 150 can accumulate between the loose powder particles 140 and solidify the powder particles 140 into a rigid, porous structure 142. Here, too, the ALD coating 150 can form at least partially on the second surface 112 of the substrate 110, although this is also uncritical.

[0046] In a final step ( Fig. 2H), the substrate 110 can be rotated back again, and the second temporary closure device 131 can be removed from the first surface (underside) of the substrate 110. This results in a substrate 110 having a plurality of through-holes 121, 122, 123 filled with loose dry powder 140 and firmly sealed at the top and bottom (i.e., on the first and the opposite second surface 111, 112) with a rigid, porous structure 141, 142, respectively.

[0047] It may be advantageous if the cavity 123 extends as straight as possible through the molded body 110 between the first and second fluid openings 121, 122. Thus, the rigid, porous structure 141 closing the first fluid opening 121 and the rigid, porous structure 142 closing the second fluid opening 122 are opposite each other.

[0048] As mentioned above, fluids, such as gases and / or liquids, can diffuse through the rigid, porous structures 141, 142 and penetrate into the cavity 123. Embodiments of the invention therefore provide that the uncoated powder particles 140 enclosed in the cavity 123 have a sorbing and / or catalytic property in order to interact with a fluid penetrating through the porous structures 141, 142 into the cavity 123. The loose particles of the powder 140 that remain uncoated can therefore also be referred to as sorption particles.

[0049] A wide variety of sensors and devices are based on the interaction of sorbent, chemically or catalytically active materials with gases or liquids. During sorption, ions, atoms, or molecules of other substances are enriched in the volume of the sorbent (absorption) or on its surface (adsorption). Absorbent materials are used, for example, in exhaust gas purification and water treatment plants or air filters to remove toxic substances. Adsorbents are widely used, for example, in chromatographic columns for substance separation or in gas detection systems for the enrichment of substances that must be detected in extremely low concentrations. Getter materials, which are used to maintain a vacuum in a closed volume, can be based either on sorption or on a chemical reaction with the gas to be bound. Catalysts accelerate chemical reactions on a surface on which they are located.

[0050] For example, the uncoated powder particles 140 enclosed in the cavity 123 can have a filtering function, so that an inflowing fluid is filtered. The device 100 according to the invention can thus be used, for example, as a microstructured active filter.

[0051] The molded body 110 can, for example, be arranged in a fluid flow such that the fluid flow penetrates into the cavity 123 through one of the two rigid, porous structures 141, 142 and exits the cavity 123 through the other of the two rigid, porous structures 141, 142. Preferably, the fluid flow can pass through the molded body 110 or the cavity 123 in the straightest possible path, i.e., without deflections. This can be made possible, for example, by designing the cavities 123 in the form of long, straight channel structures (e.g., elongated holes, trenches, etc.).

[0052] The Fig. Figures 3A to 3D show an alternative embodiment of a method according to the invention. Here, too, elements with the same or similar function are provided with the same reference numerals as in the previous figures. Therefore, the differences from the previously discussed embodiments will be discussed in more detail below.

[0053] Fig. Figure 3A shows a step during the implementation of the method which is essentially the same as in the Fig. 1C and 2D, respectively. Here, the molded body 110 has already been filled with loose powder 140, and the first fluid openings 121 have been permanently sealed by means of a rigid, porous structure 141.

[0054] A difference compared to the previously discussed embodiments is that the temporary closure device 130 is now removed first. This occurs before the mold body 110 is turned over, so that the loose powder 140 located in the cavities 123 falls out due to gravity ( Fig. 3B).

[0055] Afterward ( Fig. 3C), the molded body 110 is turned over so that the first surface 111 of the molded body 110 now forms the underside, and the second surface 112 of the molded body 110 forms the top side. Accordingly, loose, dry powder 140' can now be poured through the upper second fluid openings 122 into the previously emptied cavities 123, so that the powder 140' trickles downward due to gravity. The cavities 123 are permanently sealed on the underside with the previously formed rigid, porous structures 141, so that the newly poured powder 140' remains in the cavities 123.

[0056] The newly filled powder 140' may be a different powder than the powder 140 previously located in the cavities 123, which is in the Fig. 3B. That is, the emptied powder may be a powder of a first type, while the newly filled powder 140' may be a powder of a different second type.

[0057] The newly filled powder 140' may, for example, have a different shape and / or a different size and / or different physical / chemical properties and / or a different material than the emptied powder 140. For example, the newly filled powder 140' may have a sorbing and / or catalytic property.

[0058] Fig. 3D shows a further process step, wherein the loose, dry powder particles 140 located in the region of the second fluid openings 122 can be recoated, e.g., by means of an ALD coating, to create rigid, porous structures 142 that permanently close the second fluid openings 122. For this purpose, the cavities 123 can be completely filled with the subsequently added powder 140'.

[0059] By means of the Fig. Using the process shown in Figures 3A to 3D, a molded body 110 can be produced that is filled with loose particles 140' and is permanently sealed at the top and bottom with a rigid, porous structure 141, 142. The subsequently added particle bed 140' can be a powder that has desired properties, such as filter properties.

[0060] In short, a powder 140 of type A can be emptied, and a powder 140' of type B can then be filled into the emptied cavities 123. Thus, after the first partial solidification ( Fig. 2D) and after removal of the first temporary closure device 130 ( Fig. 2F) the remaining, non-solidified powder 140 of a first type is removed and replaced by a second powder 140' of a different type, ie the sub-step according to Fig. 2C is repeated at this point, and the remaining process steps can then be performed as described above. The second powder 140' is thus introduced into the cavities 123 above the first rigid, porous structure 141. Subsequently, the second loose powder 140' is solidified to a defined depth to mechanically fix the underlying second powder 140' in the cavity.

[0061] Preferably, the particles of the subsequently added powder 140' should be able to be agglomerated by the coating material used during coating to form the rigid, porous structures 142. If this is not the case, the cavities 123 can be only partially filled with the subsequently added powder 140'. Subsequently, the cavities 123 can then be filled with another powder (not shown here) containing coatable particles. This can, for example, be the initially used powder 140 of the first type, with which the rigid, porous structures 141 closing the first fluid openings 121 were also already created.

[0062] For all embodiments described herein, the method according to the invention can be performed at the wafer level. Accordingly, the molded body 110 can be configured in the form of a wafer, wherein this wafer has a plurality of first fluid openings 121 and oppositely arranged second fluid openings 122, each with a cavity 123 arranged therebetween. At the wafer level, all method steps described herein could be performed in parallel for all first fluid openings 121, second fluid openings 122, and cavities 123 on the wafer.

[0063] The powder to be used in the process according to the invention can consist of any material. If the powder particles 140, 140' are coated using an ALD process, the powder used should consist of a material that can withstand atomic layer deposition, typically carried out at temperatures between 60°C and 300°C, without damage. Embodiments therefore provide that the powder particles 140, 140' located in the region of the first and / or second fluid opening 121, 122 and to be coated comprise a material that can withstand a specific process temperature between 60°C and 300°C without damage. This means that not all powder particles 140, 140' per se must withstand process temperatures of up to 300°C. If the process temperature is 75°C, for example, the particles only need to withstand up to 75°C without degradation.The further processing of a shaped body 110 with such particles 140 would then also be limited to a corresponding temperature range.

[0064] Furthermore, for all embodiments, the temporary closure device 130, 131 for temporarily closing the first and second fluid openings 121, 122 can be designed, for example, in the form of a planar substrate. For this purpose, the molded body 110, for example in the sub-step according to Fig. 2B, onto the flat surface of a silicon or glass substrate. Optionally, the stack thus created can be fixed, if necessary, e.g., by clamping. In a similar way, the Fig. The temporary closure device 131 shown in Figures 2E to 2G can be replaced by a flat support.

[0065] Furthermore, the method according to the invention can be carried out with any shaped body 110. For example, the method can be applied to any substrate 110 with any thickness and any shape of through openings 121, 122, 123 that can be temporarily or reversibly sealed. Instead of a planar substrate, it can be a cavity 123 with at least one inlet 121 and at least one outlet 122 in any three-dimensional shaped body 110.

[0066] The dimensions of the inlet and outlet openings 121, 122 can be in the range of a few millimeters, preferably less than 2 mm, and particularly preferably less than 1 mm, in order to guarantee the greatest possible mechanical strength of the rigid, porous structures 141, 142.

[0067] Accordingly, the device 100 according to the invention can comprise the following: a cavity 123 in a molded body 110 with at least one inlet opening 121 and at least one outlet opening 122 located on opposite sides 111, 112, wherein the cavity 123 is filled with loose powder 140 and the inlet and outlet openings 121, 122 are closed by porous membranes 141, 142 of defined thickness, formed by agglomerating a portion of the loose powder 140 by means of atomic layer deposition. According to a conceivable development, the molded body 110 can be a planar substrate with a plurality of miniaturized cavities, wherein the cavities can be configured in the form of through-openings.

[0068] As mentioned above, the powder 140 to be used according to the invention can have sorbing and / or catalytic properties. The method according to the invention makes it possible to integrate loose, dry powder 140 into microchannels 123 in a mechanically stable manner without altering their catalytic, chemical, or sorption activity.

[0069] The microstructured device 100 to be produced using the method according to the invention can be used, for example, in microfluidics, e.g., as a sorbing filter and preconcentrator for gases and liquids. Its use as a catalytic microreactor for the chemical conversion of substances in a fluid stream, as well as miniaturized getter pumps, would also be conceivable.

[0070] Another area of ​​application would be the packaging and interconnection technology (AVT) for MEMS environmental sensors, i.e. their protection against harmful influences from the environment with which these sensors are intended to interact, e.g. the catalytic removal of ozone from the ambient air, or the binding of siloxanes from the ambient air.

[0071] The with reference to the Fig. The method according to the invention for producing a miniaturized device 100 filled with loose powder particles 140 described in FIGS. 3A to 3D can be summarized as follows.

[0072] One method step includes providing a molded body 110 with a first fluid opening 121, a second fluid opening 122 arranged opposite, and a cavity 123 arranged therebetween.

[0073] A further method step includes closing the second fluid opening 122 by means of a temporary closure device 130, which is attached to the molded body 110 in the form of a detachable connection, while the opposite first fluid opening 121 remains open and accessible.

[0074] A further method step includes filling the cavity 123 with a loose powder 140 of a first type, wherein the loose powder 140 is filled through the openly accessible first fluid opening 121.

[0075] A further method step includes solidifying powder particles located in the region of the first fluid opening 121 using a coating process, wherein the powder particles solidified by means of the coating form a rigid, porous structure 141 which permanently closes the first fluid opening 121.

[0076] A further method step includes removing the temporary closure device 130 closing the opposite second fluid opening 122 so that the second fluid opening 122 is openly accessible.

[0077] A further method step includes removing uncoated powder particles 140 of the first type from the cavity 123 and filling a loose powder 140' of a second type into the cavity 123 through the openly accessible second fluid opening 122.

[0078] A further method step includes solidifying powder particles 140' of the second type located in the region of the second fluid opening 122 using a coating process, wherein the powder particles solidified by means of the coating form a rigid, porous structure 142 which permanently closes the second fluid opening 122.

[0079] As a result, a microstructured device 100 according to the invention is obtained in which uncoated powder particles 140' of the second type are permanently enclosed in the cavity 123 by means of the porous structures 141, 142 closing the respective fluid openings 121, 122.

[0080] According to one embodiment of this method, the first rigid, porous structure 141 permanently closing the first fluid opening 121 contains coated powder particles 140 of the first type, and the second rigid, porous structure 142 permanently closing the second fluid opening 122 contains coated powder particles 140' of the second type.

[0081] The above-described embodiments merely illustrate the principles of the innovative concept described herein. 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 concept described herein 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.

[0082] 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.

Claims

[1] A method for producing a microstructured device (100) filled with loose powder particles (140), the method comprising the following steps: Providing a molded body (110) with a first fluid opening (121), a second fluid opening (122) arranged opposite and a cavity (123) arranged therebetween, Closing the second fluid opening (122) by means of a temporary closure device (130) which is attached to the molded body (110) in the form of a detachable connection, while the opposite first fluid opening (121) remains open and accessible, Filling the cavity (123) with the loose powder particles (140), wherein the loose powder particles (140) are filled through the openly accessible first fluid opening (121), Solidifying loose powder particles (140) located in the region of the first fluid opening (121) using a coating process, wherein the powder particles solidified by means of the coating form a first rigid, porous structure (141) which permanently closes the first fluid opening (121), Removing the temporary closure device (130) closing the opposite second fluid opening (122) so that the second fluid opening (122) is openly accessible, Solidifying loose powder particles (140) located in the region of the second fluid opening (122) using a coating process, wherein the powder particles solidified by means of the coating form a second rigid, porous structure (142) which permanently closes the second fluid opening (122), wherein loose powder particles (140) which remain uncoated are permanently enclosed in the cavity (123) by means of the first and second porous structures (141, 142) which close the respective fluid openings (121, 122). [2] Method according to claim 1, wherein the following step is carried out before the step of solidifying the loose powder particles (140) located in the region of the second fluid opening (122): Removing uncoated loose powder particles (140) from the cavity (123) through the second fluid opening (122) which is still open at this time, and subsequently filling the cavity (123) with loose powder particles (140') of a different second type, wherein the loose powder particles (140') of the second type are filled through the openly accessible second fluid opening (122). [3] Method according to one of the preceding claims, wherein the temporary closure device (130) for temporarily closing the second fluid opening (122) is designed in the form of a film which is laminated onto the shaped body (110). [4] Method according to one of the preceding claims, wherein the following step is carried out before the step of solidifying the loose powder particles (140) located in the region of the second fluid opening (122): Closing the first fluid opening (121) together with the first rigid, porous structure (141) formed therein by means of a second temporary closure device (131) which is attached to the shaped body (110) in the form of a detachable connection. [5] Method according to claim 4, wherein the second temporary closure device (131) for closing the first fluid opening (121) is designed in the form of a film which is laminated onto the shaped body (110). [6] A method according to any one of the preceding claims, wherein the coating process for solidifying the loose powder particles (140) is carried out using atomic layer deposition. [7] Method according to claim 6, wherein the thickness of the respective first and second rigid, porous structures (141, 142) is determined by a penetration depth of the coating material deposited during the atomic layer deposition, and wherein the atomic layer deposition is carried out such that the penetration depth of the deposited coating material is less than 30%, or less than 10%, of the total height of the powder particles (140) located in the cavity (123). [8] Method according to claim 6 or 7, wherein the atomic layer deposition is carried out at a process temperature between 60°C and 300°C, and wherein the powder particles (140) to be coated located in the region of the first and / or second fluid opening (121, 122) comprise a material that can withstand a specific process temperature between 60°C and 300°C without damage. [9] Method according to one of the preceding claims, wherein the uncoated powder particles (140) enclosed in the cavity (123) have a sorbing and / or catalytic property in order to interact with a fluid penetrating into the cavity (123) through the first and second rigid, porous structures (141, 142). [10] Method according to one of the preceding claims, wherein the first and / or second fluid opening (121, 122) each have a diameter of less than 2 mm, or less than 1 mm. [11] Method according to one of the preceding claims, further comprising: Orienting the molded body (110) such that the temporary closure device (130) for closing the second fluid opening (122) is arranged on an underside of the molded body (110) in order to secure the loose powder particles (140) located in the cavity (123) against falling out due to gravity. [12] Method according to claim 11, wherein the openly accessible first fluid opening (121) is arranged on an upper side of the molded body (110) so that the loose powder particles (140) can be filled into the cavity (123) from above and can trickle into the cavity (123) due to gravity. [13] Method according to claim 11 or 12, wherein after the step of solidifying the powder particles (140) located in the region of the first fluid opening (121), the molded body (110) is rotated so that the first fluid opening (121) permanently closed by the first rigid, porous structure (141) is located on an underside of the molded body (110) in order to secure the loose powder particles (140) located in the cavity (123) against falling out due to gravity. [14] Method according to one of the preceding claims, wherein the shaped body (110) is designed in the form of a planar substrate, and wherein the first fluid opening (121) is designed in the form of an opening in a first main surface (111) of the substrate, wherein the second fluid opening (122) is designed in the form of an opening in a second main surface (112) of the substrate opposite the first main surface (111), and wherein the cavity (123) is designed in the form of a hollow space extending between the first and second fluid openings (121, 122). [15] Method according to one of the preceding claims, wherein the process is carried out at wafer level, wherein the shaped body (110) is designed in the form of a wafer, said wafer having a plurality of first fluid openings (121) and oppositely arranged second fluid openings (122), each with a cavity (123) arranged therebetween, and wherein the method steps according to claim 1 are carried out in parallel for all first fluid openings (121), second fluid openings (122) and cavities (123) on the wafer. [16] Microstructured device (100) filled with loose powder particles (140), comprising: a molded body (110) with a first fluid opening (121), an oppositely arranged second fluid opening (122) and a cavity (123) arranged therebetween, wherein the first fluid opening (121) is permanently closed by a first rigid, porous structure (141), wherein the first rigid, porous structure (141) comprises powder particles solidified by means of a coating process, wherein the opposite second fluid opening (122) is permanently closed with a second rigid, porous structure (142), wherein the second rigid, porous structure (142) comprises powder particles solidified by means of a coating process, and uncoated loose powder particles (140) permanently enclosed in the cavity (123) between the first rigid, porous structure (141) and the opposite second rigid, porous structure (142).

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