Fabrication and production of customized three-dimensional micro- and nanostructures using surface coating technologies via sacrificial structures consisting of polar / ionic matrices

Abstract

In the first step of the manufacturing process according to the invention, matrices in the form of hollow structures are printed as negatives using a 3D printer. Materials soluble in common solvents are used as the starting material. These soluble materials are printed with the intention of being dissolved in a later step of the manufacturing process. Preferably, the most common soluble filament materials, such as HIPS and PVA, are used. In the second step, these hollow structures (and thus their surfaces) can be coated from the inside and, if necessary, also (partially) from the outside using highly temperature-sensitive coating processes such as chemical vapor deposition (CVD) or chemical vapor infiltration (CVI) with the aid of suitable precursor compounds, so that structures are created as positives on the surfaces of the hollow structure (matrix). For this purpose, suitable precursors are provided, enabling for the first time the deposition on and in such matrix materials that could not previously be coated; certainly not in the form of negatives produced by 3D printing, since these matrix structures are, in some cases, very temperature-sensitive materials. In the third and final step, the negative is dissolved in a suitable solvent (e.g., water for PVA or limonene for HIPS) to separate it from the contiguous structure, thus removing the positive from the negative. The released positive structure forms the desired component. After purification from any remaining matrix material, the resulting micro- or nanocomponent is ready for use.

Description

State of the art

[0001] Micro- and nanocomponents are playing an increasingly important role in a wide variety of technical fields. However, such components, and especially highly specialized ones in the micro and nano range, are currently very difficult or even impossible to manufacture.

[0002] The fabrication of intricate, three-dimensional micro- and nano-fluid structures made of metal or metal compounds with complex geometries is a challenging topic in micro- and nanotechnology. Such three-dimensional (spatial) micro- and nano-fluid structures have a wide range of applications in micro- and nanotechnology, such as in micro- and nanofluidic applications, as components in micro- and nanoelectronics, or in micro- and nanomechanics, for example as micro- and nanomachines.

[0003] The production of such microcomponents is partly carried out using conventional manufacturing processes that have also proven successful in macrotechnology, such as pressing, casting, rolling or forming [wiki1] - [wiki2], [Schu1] - [Schu2], [Voll1] - [Voll2].

[0004] A special method for manufacturing metallic microcomponents is laser-assisted wet chemical etching of metal substrates. In this process, the metal substrate is immersed in an etching liquid (acid, alkali). While the liquid itself does not attack the metal surface—at least not during a relatively short exposure time—material removal from the metal surface is activated by a laser beam (e.g., an argon or krypton ion laser), with the laser beam guided along the resulting ablation channel [Now1] - [Now3]. However, the production of such components is limited to relatively simple geometries. Complex geometries with intricate features on the scale of the lower micrometers, e.g.,Thin, finely branched microfluidic structures with diameters of just a few micrometers and wall thicknesses even in the sub-micrometer range have been very difficult to produce using conventional methods. Since the 1980s, 3D printing has offered a way to realize such delicate, metallic micro(fluid)structures with complex geometries [dnat1].

[0005] 3D printing is a so-called additive manufacturing process in which the desired three-dimensional component is produced by layering of starting material in liquid or powder form with subsequent curing (e.g. polymerization, sintering) [wiki3].

[0006] A computer-controlled 3D printer is used as the appropriate additive manufacturing device, which performs the layer-by-layer application of the filament in a predefined manner. Curing can be achieved either physically, for example by applying heat or by applying radiant energy (e.g., electromagnetic radiation such as synchrotron, gamma, X-ray, UV, vis, IR, or RF / microwave radiation, or particle radiation such as atomic, ionic, electron, or radioactive radiation), or chemically, for example, by adding reaction initiators.

[0007] Ceramic powders achieve hardening through a sintering process. Various metals in powder form, polymers (plastics) in powder form, synthetic resins in liquid form, or ceramics in powder form can be used as starting materials [dna1] - [dnat2]. Due to its high melting point, glass in the form of quartz glass powder has not been particularly suitable as a starting material for 3D printing technology. However, by adding substances such as barium, the softening points can be significantly lowered compared to pure quartz glass, so that the use of glass powders would also be conceivable according to the invention. Alternatively, powdered plastics can be used.

[0008] The different types of 3D printing are distinguished based on their different functional and operating principles and partly on different starting materials, with SLA (stereolithography; starting material usually liquid such as liquid resin), FDM / FFF (fused deposition modeling; starting material usually powdery such as metal, plastic or ceramic powder) and SLS (selective laser sintering; starting material usually powdery such as metal, plastic or ceramic powder) being the most important 3D printing technologies [dnat3] - [dnat4].

[0009] Two other 3D printing technologies that can use plastics as a starting material are "Material Jetting" and "Multi Jet Fusion". However, these play a rather minor role in a few technological niches.

[0010] German patent applications DE 10 2016 002 183 A1 and DE 10 2018 009 670 A1 disclose a femtosecond laser-based method for generating spatial microchannel and micro-optical structures. In this method, a three-dimensional, intricate structure is written within the volume of a transparent material using the focus of a femtosecond (fs) laser beam. This method exploits the fact that, due to the very high intensities, multiphoton processes are triggered in the material only at the focus of the fs laser. These processes modify the material so that it becomes solvent-soluble; however, this occurs only within the focus area, not outside of it. If this three-dimensional, intricate structure is connected to the surface, it can be washed out or removed with suitable solvents.extract, so that a corresponding three-dimensional, delicate cavity structure is created, the geometry of which corresponds to the three-dimensional, delicate structure inscribed with the focus of the fs laser.

[0011] Several MOCVD processes are already known from the SdT for the internal coating of capillary structures with a thin metal layer: German patent application DE 10 2007 020 800 A1 discloses a method for a modified multichannel structure, in which the multichannel structure has at least 10, preferably at least 100, particularly preferably at least 1000, and most preferably at least 10,000 channels, and an internal coating and / or particles are introduced into the channels of the multichannel structure. The invention also relates to methods for producing the modified multichannel structure and its use.

[0012] DE 10 2007 049 929 B4 discloses a method for internally coated hollow optical waveguides, wherein the hollow optical waveguide a) a channel structure and b) an internal coating on the inner surface of the channel structure comprising, wherein the surface of the inner coating facing the channel interior has a height of less than 50 nm.

[0013] Both disclosures use the same MOCVD for modifying the channel interiors, however, in contrast to this invention, the channel structures are retained in both methods even after completion.

[0014] Other metal coating processes, also for microstructures, are provided by electroplating and electrodeless metallic deposition processes. Task

[0015] A method and the corresponding apparatus, as well as the micro- and nanostructures obtained therefrom, are disclosed for the fabrication of highly intricate, three-dimensional micro- and nanostructures with complex geometric designs. These are primarily hollow structures (micro- and nanofluid structures) with a diameter of a few micrometers to nanometers (i.e., in the lower micrometer or nanometer range) and a wall thickness in the sub-micrometer range; however, solid, three-dimensional micro- and nanostructures without a cavity are also conceivable using the disclosed method. General solution approach

[0016] The basic idea of ​​this invention is the combination of several already known technologies to produce complex, spatial, preferably metallic or metal-containing micro- and nanostructures, which are urgently needed in micro-technology but especially for nanotechnology.

[0017] As already mentioned, this approach draws on individual, proven technologies that have been known and tested in isolation for many years. However, the combination of these individual, known, and proven technologies into a novel process chain—specifically for the production of these metallic micro- and nanostructures—is unprecedented and must therefore be considered new. This original invention must thus be viewed within the context of all these technologies together in a process chain where all steps are perfectly coordinated and therefore belong together, and which cannot be disassembled or separated to achieve the stated goal.

[0018] Broadly speaking, this process chain consists of the following three steps or stages (see Fig. 1): 1) Production of the negative: Creation of micro- or nanohollow structures within the volume of the starting substrate:

[0019] In the first step of the process chain, a three-dimensional micro- or nanohollow structure is created in the volume of a starting substrate consisting of a starting material (polymer, ceramic, glass, etc.).

[0020] This starting material is also referred to below as the matrix material, and the associated micro- or nanohollow structure as the matrix (structure) or simply as the negative. Various technologies can be used to produce these micro- or nanohollow structures (matrix structures), such as 3D printing or the femtosecond laser (fs) radiation-based process already described in the "State of the Art" chapter, with subsequent rinsing of the modified zone. In this process, the focus of the fs laser beam moves along the desired geometric path of the micro- or nanohollow structure, so that the material impacted by the laser is defragmented and finally rinsed away with a suitable solvent.

[0021] The resulting micro- or nanohollow structure, forming a negative, is merely a kind of "auxiliary structure," serving only as a "support structure" or "support material" (also called "support structure" or "support material"). Its purpose is to provide support and shape to the preferred metal or metal-containing layers deposited in the subsequent coating process, thus serving as a temporary support material (see the second stage of the process chain discussed below in section 2). At the same time, this negative, as a "support structure," is also a "sacrificial structure" that is ultimately completely removed later in the process chain (see also the third stage of the process chain discussed below in section 3). 2) Production of the positive: Coating of the surfaces of the micro- or nanohollow structure.

[0022] In the second step of the process chain, the negative surfaces, i.e., the inner surfaces and, if applicable, the outer surfaces of the micro- or nanohollow structure, which were already produced in the first step of the process chain (see point 1 above), are then (partially) coated and preferably metallized using various coating processes alone or in combination with each other, in particular preferably using the CVD process or the CVI process, and especially preferably the CVD process or the CVI process with organometallic or organometallic or complex compounds, i.e., the application of a preferably metallic or metal-containing thin film to the inner surfaces and, if applicable, the outer surfaces of the micro- or nanohollow structure, which allows the suitable gaseous CVD or CVI precursor materials to flow through the micro- or nanohollow structures produced in the first step of the process chain (see point 1 above).However, other metallization processes of electroplating, as well as CLD (chemical liquid phase deposition) and electroless metallization, can also be used according to the invention to produce such micro- and nanostructures.

[0023] In addition to the MOCVD process for depositing thin films on the inner surfaces and, if necessary (partially), also on the outer surfaces (negative structure), the following should also be added: The inner and outer coating of the micro- and according to the invention Nanostructures formed by thin-film coatings typically contain an element from groups 2 to 5 or a subgroup of the periodic table and preferably contain an element selected from the group consisting of Ca, Mg, Al, Be, Ni, Pt, Cu, Pd, Ag, W, Re, Ir, Os, Au, Pb, Bi, and U, wherein the elements Ca, Mg, Al, Ni, Ag, Au, W, Os, Pd, Pt, Bi, and U are particularly preferred. In a further preferred embodiment, the element from groups 2 to 5 of the periodic table is other than carbon.

[0024] In another preferred embodiment, the inner and (partial) outer coating contains a metal with an atomic number Z > 10. 3) Release of the positive: Elimination or removal of the initial matrix material to expose the three-dimensional micro- or nanostructures:

[0025] Finally, in the third and last step of the process chain, the initial matrix material, which serves as a "carrier material" / "support structure" for the element layers and structures, is removed. This can be done either by dissolving the negative that serves as the "carrier or matrix material".

[0026] This negative can preferably consist of glass and particularly preferably of a (polymeric) starting material, which is preferably etched away by a suitable etching agent (etching away the area of ​​the (glassy) starting material, that have not been targeted by the focus of the fs laser beam) or especially when removed by a suitable solvent, so that ultimately only a micro- or nanostructure remains as the desired positive. which consist of a network of interconnected and The resulting structure consists of (partially) bonded, preferably metallic or metal-containing thin films on the inner and outer surfaces of the micro- or nanohollow structure. This process ultimately creates the desired micro- or nanocomponents.

[0027] It is up to the user to decide whether the resulting spatial micro- or nanostructure is either solid (and therefore mechanically resilient) or hollow (and thus itself a micro- or nanostructure).

[0028] The starting material in which the micro or nanohollow structure is embedded therefore plays, in addition to its role as a support or negative material, the role of a "sacrificial material," which is only necessary to deposit the particularly preferred metal layers on the surfaces of the inner and, if applicable, outer surfaces of the micro or nanohollow structure. Ultimately, the "sacrificial material" is then removed by etching and preferably by dissolving it in a suitable solvent, so that this "support structure" is no longer present in the final product, leaving only the desired three-dimensional, particularly preferred metallic micro or nanostructure as the final product.

[0029] The selection of this starting or matrix material must be such that, firstly, its surface is not attacked or destroyed by the thin-film deposition process, but secondly, it can be quickly removed by a solvent or etchant A, as it is readily soluble or etchable with respect to the applied solvent or etchant A.

[0030] In the case of the femtosecond laser-based method for fabricating micro- or nanohollow structures, the starting or matrix material used must be modifiable by the femtosecond laser radiation at the focus, i.e., at very high intensities, so that after modification by focused femtosecond laser radiation, it can be dissolved or etched by another solvent or etchant B, allowing the modified material to be washed out of the matrix structure to create the three-dimensional hollow structures. Solvent or etchant B must not be identical to the solvent or etchant A used to ablate or remove the micro- or nanohollow structures (matrix structures).

[0031] In the case of 3D printing as a build-up manufacturing process for generating matrix or negative structures, the starting or matrix material must be machinable through the 3D printing process in order to build the desired three-dimensional negative structures.

[0032] It is not yet foreseeable whether all these requirements, which determine the selection of the matrix material, are always compatible with each other or whether they partially contradict each other. For further information, please refer to the explanations below. Specific and special examples of implementation: 1.) Production of the negative: Creation of micro- or nanohollow structures within the negative (volume of the starting substrate)

[0033] In the first step of the process chain (1.) “Generation of microchannel structures within the negative (volume of the starting substrate)”), various technologies that are already known and proven can be used: The application of the so-called 3D printing process for the production of micro- and nanohollow structures within the volume of a starting substrate is particularly preferred.

[0034] First, the appropriate starting material for the 3D printing process is selected and provided in sufficient quantity and form. Within the scope of this invention, polymers in powder form are preferably used as the starting material for 3D printing [dnat1]. These include, among others, ABS (acrylonitrile butadiene styrene), a mechanically very flexible, yet impact-resistant and thermally very stable thermoplastic, which is, however, not biodegradable; ASA (acrylonitrile styrene acrylate) with similar properties to ABS, but more resistant to UV radiation; and PET (polyethylene terephthalate), a semi-rigid, highly resistant plastic material that is, among other things,in the beverage industry as a raw material for plastic bottles and includes the various sub-types PETG (glycolized polyester), PETE and PETT, and PC (polycarbonate) as a very resistant polymeric material, and the high-performance plastics PEEK (polyetheretherketone), PEKK (polyaryletherketone), and ULTEM (polyetherimide), and PP (polypropylene), a common and industrially widespread standard plastic worldwide, as well as various common types of polyamides.

[0035] In particular, soluble polymer materials such as HIPS (High Impact Polystyrene), PVA (Polyvinyl Acetate) and BVOH filaments (Butenediol Vinyl Alcohol Copolymer) are especially suitable for the process according to the invention and are therefore particularly preferred.

[0036] Polymer structures consisting of . PVA can be completely dissolved without residue in water with a water temperature of 70°C, which is why PVA is one of the biodegradable polymers and is therefore unproblematic from an ecological point of view [dnat5].

[0037] From an environmental perspective, PLA (polylactides or polylactic acids) should also be explicitly mentioned, as this polymer is particularly biocompatible and biodegradable and therefore sustainable [dnat1] - [dnat2].

[0038] Combinations of PLA and PVA as starting materials are particularly preferred, combining the advantages of both polymers [dnat5]. Other sustainable materials include wood, cork, or even coffee filaments [dnat6] - [dnat7], some of which are also soluble in water, alcohol, or organic solvents such as hexane, heptane, chloroform, benzene, etc. If PVA is selected as the starting material, a sufficient quantity in powder form can be fed into an FDM printer [dnat5].

[0039] In the case of a powder mixture of PLA and PVA powder, an FDM dual extrusion machine can also be used [dnat8]. The same applies to BVOH filaments as a starting material [dnat1], [dnat8]. However, storing PVA is not entirely straightforward (regardless of whether it is used alone or as a mixture with another polymer powder), as care must be taken to ensure that PVA is stored relatively cool (approximately 15°C to 25°C) and protected from light and dust. However, for pure PVA powder as a starting material for 3D printing, an FDM print head is sufficient, which must be operated at a printing temperature between 180°C and 225°C. Furthermore, according to [dnat5], the heated bed should have a temperature of 60°C to a maximum of 90°C during printing; ideally, the temperature should be kept towards the lower end of this range. An important point to consider when working with PVA is the extruder configuration.Allowing the PVA hotend to cool down while idling prevents leakage and clogging.

[0040] The fabrication of microchannel structures within the volume using a focused femtosecond (fs) laser beam followed by rinsing the zones treated with focused fs radiation and thus modified is less preferred, since firstly the selection of material for the starting substrate (starting material) is severely limited and secondly preliminary tests have shown that the samples with microhollow structures produced in this way exhibit such a large number and density of errors and defects in the volume and on the surface of the sample, to such a high degree, that they are simply unusable for the subsequent second and third stages of the process chain or at least their usability is clearly very borderline.

[0041] Furthermore, spatial micro- or nanohollow structures can only be created with a limited degree of complexity using this method, not with arbitrary geometry. This is because gaseous defragmentation products are generated when the volume is subjected to femtosecond laser radiation. These products must be removed to prevent the hollow structures from expanding and thus deforming. Therefore, these hollow structures are characterized by regularly arranged venting channels that are connected to the surface at short intervals.

[0042] Furthermore, it is not yet possible to create nanohollow structures with this method, partly due to the existing technological difficulties of focusing the fs laser radiation with a focusing caustic in the nanometer range.

[0043] The advantage of the fs-laser-based method, however, is that it has already been successfully used in other areas, for example in the processing of photosensitive glass materials, so that there is a certain wealth of experience in dealing with this technology.

[0044] Any material that is transparent in the visible range and otherwise of very good optical quality can serve as the starting material, especially glass and plastics, so that the femtosecond laser beam is not disturbed by material influences (such as absorption, birefringence or spatial refractive index fluctuations, etc.) in the volume of the starting substrate consisting of the starting material and can thus be focused unhindered.Furthermore, the materials serving as starting materials must be modifiable at the focus after being subjected to focused femtosecond laser radiation of extremely high intensity, so that multiphoton processes can take place in the zone of the material irradiated by the focus, associated with a modification of the material in this irradiated zone (usually in the form of degradation or defragmentation), so that the zone modified by femtosecond laser radiation becomes soluble or etchable with certain solvents or etchants: By a subsequent action of a first fluid medium, more precisely a suitable solvent, on the zone irradiated at the focus of the laser beam, the modified and thus degraded or defragmented starting material must be able to be dissolved, washed out, or rinsed out after such femtosecond laser-based processing (see also the first stage of the process chain).

[0045] Furthermore, the areas of the starting material not exposed to the focus of the femtosecond laser radiation must be soluble or etchable by treatment with a further, different, second fluid medium, a solvent or etchant (see third stage of the process chain). However, this other, second medium, namely the etchant, must not be identical to the first medium, the solvent, and the first medium, the solvent, must not attack the areas of the starting material not exposed to the focus of the laser beam, i.e., the starting material in its original, unmodified state, just as it must not attack the metal used for metallization (see second step of the process chain) from which the deposited metal thin film consists, and thus must also not attack this deposited metal thin film.because, after rinsing in the first step of the process chain, residues of the solvent may still be present in the micro- or nanohollow structures, and these must not prevent the deposition of the metal thin film.

[0046] The latter point, namely that the metal of the thin-film must not be attacked, also applies, and even more so, to the second fluid, the etchant; this too must not attack the metal used for metallization, so that it does not destroy the metal layer deposited inside the micro- and nanohollow structure when the matrix structure is dissolved or etched away by it. At the very least, the solubility or etch rate of the metal must be many orders of magnitude lower with respect to the second fluid than with respect to the matrix material.

[0047] The first fluid, i.e., the solvent, refers to the first step of the process chain, while the second fluid, i.e., the etchant, refers to the third step of the process chain, so that these two fluids are not used simultaneously and therefore should not interact with each other.

[0048] Based on this complex mix of different boundary conditions, especially the starting material with regard to the fluids (solvents and etchants), it is easy to see that this situation can have a very limiting effect on the selection of starting materials for fs-laser-based production of micro- and nanohollow structures.

[0049] As an alternative to an etching agent, i.e., instead of the etchability of the material untreated with femtosecond laser radiation, the material can also be burned, destroyed, vaporized, or generally ablated when exposed to suitable heat. Thus, ablation can occur not only through the action of a solvent or etching agent (chemical pathway) but also through the application of heat (thermal pathway). A furnace (heat convection) or a hot plate (heat conduction) can be used as the heating medium. Theoretically, thermal ablation through the radiation of an infrared light source / IR emitter, such as a CO2 laser (photothermal via heat radiation), also appears possible instead of heat from a furnace (heat convection) or hot plate (heat conductivity). The application of other photo- or light-based (photolytic instead of photothermal) ablation methods cannot be ruled out either.

[0050] This alternative method of thermal ablation is particularly interesting with regard to plastics; certain photosensitive glasses (glasses impregnated or doped with photosensitizers) could also be available for a photo-based ablation process.

[0051] The advantage of the femtosecond laser-based method for microchannel generation compared to 3D printing is that glass can be used as a starting material with the femtosecond laser; this is not currently possible with 3D printing technology. However, glass as a starting material also has the disadvantage that etching rates are very low, meaning that removing the sometimes quite thick starting material by etching takes a very, very long time (usually weeks to several months). Therefore, from the current perspective, the use of glass as a matrix material is limited to very specific applications where process times are not critical.

[0052] In contrast, plastics have the advantage over glass that they can be removed much faster and more easily, for example, using suitable solvents or thermally. While it is conceivable that plastics could also be used as a starting material for the femtosecond laser-based method for micro- or nanochannel fabrication, this would also lead to other problems, including the following: Suitable plastics must be found that can be processed in a suitable manner using the fs laser-based method.

[0053] As starting materials for the femtosecond laser-based fabrication of micro- and nanohollow structures, glasses such as Duran glass, BK 17 or other BK grades, borosilicate glasses, quartz glass, calcium fluoride glass materials, or entirely different types of glass can be used. Suitable plastics include PMMA and derivatives, PBMA, PMMI, PC, PS, PE, PP, PET, polycellulose, and also halogenated polymers, especially fluoropolymers and chloropolymers such as Teflon.

[0054] For the reasons or difficulties mentioned above, the use of ceramics, metallic materials or composite materials or natural materials or materials based on them, such as wood or paper, for the production of microhollow structures using the fs laser-based method appears less suitable, as these materials do not meet the above-mentioned conditions or only to a small extent. 2.) Production of the positive: Coating of the surfaces of the micro- or nanostructure

[0055] After the micro- or nanohollow structures have been created within the volume of the starting substrate, in the second step of the process chain ("coating of the inner and outer surfaces of the micro- or nanohollow structure") the inner and, if applicable, the outer surfaces of the micro- or nanohollow structure are (partially) coated or metallized, i.e. a thin, but as essentially continuous and continuous as possible (metal) layer is applied to the inner and, if applicable, the outer surfaces of the micro- or nanohollow structure.

[0056] The coatings can consist, for example, of pure metal layers, metal oxide layers, or metal carbide layers. The layer thickness can preferably range from the sub-micrometer to the lower micrometer range. However, greater layer thicknesses are also possible. The layer can be uniformly thick across the entire surface or vary in thickness depending on location. This creates a further (metallic) micro- or nanofluid structure within the micro- or nanohollow structure in the starting substrate, which itself also contains a cavity. Optionally, the thickness can be significantly greater than a few micrometers; complete metallization of the micro- or nanohollow structures is also conceivable, so that the volume of the micro- or nanohollow structures is completely filled with the metal, resulting in a solid metal structure without its own cavity within the micro- or nanohollow structures.

[0057] Various technological methods or procedures can be used to deposit the preferably metallic (thin) film.

[0058] Gas-phase methods are preferred, with the so-called CVD or CVI method being particularly preferred: Examples of gas-phase processes include chemical vapor deposition (CVD), chemical vapor infiltration (CVI), and physical vapor deposition (PVD). Processes are particularly suitable in which the inner or outer coating is applied to or embedded in micro- and nanohollow structures using chemical vapor deposition of organometallic compounds, such as chemical vapor deposition of organometallic compounds (OMCVD), chemical vapor infiltration of organometallic compounds (EOCVD), such as chemical vapor infiltration of organometallic compounds (OMCVI), or gas-phase epitaxy of organometallic compounds, such as gas-phase epitaxy of organometallic compounds (OMVPE).The term “organic compound” here refers in particular to a compound that contains an element other than carbon from the second to fifth main group or a subgroup of the periodic table of elements, as well as organic groups and / or carbonyl groups that are chemically bonded directly and / or via an element of the fifth or sixth main group to the respective element.

[0059] Suitable organometallic compounds for gas-phase processes include, in particular, complex or coordination compounds containing an organic ligand and / or a carbonyl group. Complex or coordination compounds containing a ligand selected from the group consisting of a carbonyl, hexafluoroacetylacetonato, and acetylacetonato group are preferred.

[0060] Coating processes that use high temperatures or energies, such as physical vapor deposition (PVD) or chemical vapor deposition (CVD), can easily destroy the thin and delicate, but also very temperature-sensitive micro- and nanohollow structures due to the energy exposure.

[0061] Chemical vapor deposition (EOCVD) or chemical vapor infiltration of organometallic compounds (EOCVI), in particular chemical vapor deposition of organometallic compounds (OMCVD), provide coating processes that allow coatings of such micro- and nanohollow structures to be carried out at relatively low temperatures without irreversibly damaging or destroying the thin (channel) walls of these structures.

[0062] The method according to the invention is particularly suitable for modifying micro- and nanohollow structures with special or complex structures. The application of other CVD and PVD methods (individually or in combination), especially liquid CVD (in which a metal layer is deposited onto the surface from a liquid phase), is also conceivable. The invention also relates to a method for producing the micro- and nanostructures according to the invention. This method is characterized in that the internal coating is introduced into the micro- or nanohollow structures by a wet chemical process (for example, wet chemical impregnation, dip coating), a photolytic process (for example, laser coating), an electrochemical process (for example, an electrochemical coating process), a plasma technology process, or a gas-phase process.Wet chemical processes for introducing internal or external coatings into microhollow structures are particularly applicable to structures whose internal channels have a diameter of at least 400 µm. Especially with relatively small internal channel diameters, it is advantageous to add a wetting agent to the coating solution. Examples of suitable wetting agents include sulfates of unbranched primary cyano-cis alcohols, such as sodium lauryl sulfate, and benzenesulfonates substituted with preferably branched cyano-cis alkyl groups, such as sodium dodecylbenzenesulfonate. Suitable commercially available wetting agents include, for example, wetting agents H 135 and DL from Enthone, Inc., West Haven, CT, USA.

[0063] As an alternative metallization method to the EOCVD or EOCVI process, electroless electroplating can also be used to deposit a metallic thin film onto the inner surfaces of the microchannel structures, in which an external circuit can be dispensed with, i.e. it does not require the application of an external voltage or current source, which means a reduced equipment requirement.

[0064] For electroless plating, a suitable electrolyte solution is introduced into the micro- or nanohollow structures. The metal to be deposited is dissolved in this solution in the form of cations, and a redox reaction known as cementation seals the inner surfaces of the micro- or nanohollow structure with a thin metallic film. A disadvantage of this method is that a saturation effect prevents the layer thickness from being exceeded. The layer thickness is usually adjusted by the process duration (i.e., the contact time of the electrolyte solution with the surface) and the metal cation concentration of the electrolyte solution. Therefore, it is not very variable and can only be controlled to a limited extent and very slowly.

[0065] The electroless metallization process can be carried out in different embodiments: In addition to the contact method, the electroless chemical coating process can also be used, although this process differs. The technical details are familiar to those skilled in the art from the generally known prior art.

[0066] Another possible, though less preferred, metallization method for the inner surfaces of micro- and nanohollow structures is, of course, the classic electroplating process with suitable electrodes, operated by an external circuit, i.e., an external voltage or current source. Such an electroplating process is also familiar to those skilled in the art from the relevant literature.

[0067] The application of solid-state electrolysis, in which a powdered or viscous but still flowable electrolyte, e.g., in the form of a high-viscosity gel, is introduced into the micro- or nanohollow structures to deposit a metal layer onto the inner surface of the microchannel structures via solid-state electrolysis, also appears feasible. The application of other metallization methods, such as sputtering, capillary electrophoresis, capillary coating, liquid epitaxy, vapor-liquid-solid (VLS) processes, and other methods, as exemplified in publication US 2015 / 0280228 A1, also seems conceivable, albeit in a different context, for metallizing the inner surfaces of the microchannel structures.

[0068] The advantages of the EOCVD and EOCVI processes compared to other alternative metallization methods, such as electroless metallization, lie in the improved controllability of the deposited metal thin films and the wider range of possible thickness variations. The ability to adjust layer thicknesses in electroless metallization is very limited, whereas the MOCVD / MOCVI process allows for the production of much thinner and much thicker metal films. Since, unlike electroless metallization, there is no upper limit to the possible layer thickness, and the process parameters of MOCVD / MOCVI allow for the production of much thinner metal films, even down to the sub-micrometer range, and therefore also metallic atomic monolayers (ALDs).

[0069] This allows for the realization of much finer and more delicate metal layer structures and thus much finer and more delicate three-dimensional metallic micro- and nano(fluid) structures than with other metallization processes, since much finer micro- and nanohollow structures can be surface coated using MOCVD / MOCVI than with other alternative metallization processes.

[0070] Hybrid metal layers can also be produced very easily using MOCVD / MOCVI, since the process or deposition parameters can be varied dynamically over time much more effectively than with other metallization methods. Therefore, for example, a thin metal layer of metal type A with a thickness d1 is first deposited, followed by a second thin metal layer of metal type B with a thickness d2, and finally, a monolayer of metal type C is deposited on top of the second, upper metal layer of metal type B.

[0071] Such hybrid metal thin-film systems can only be realized to a very limited extent with electroless metallization, since the type of metal dissolved in the electrolyte solution and to be deposited must always be less noble than the already deposited metal layer onto which the new metal layer is to be deposited.

[0072] MOCVD / MOCVI may also deposit locally varying metal layers with respect to thickness, metal type, or other (quality) characteristics. 3.) Release of the positive: Removal of the starting material to expose the three-dimensional: metallic micro- or nanostructures

[0073] In the third and final step of the process chain ("removing the starting material to expose the three-dimensional micro- or nanostructures"), the starting material forming and surrounding the micro- or nanohollow structures (matrix structures) is treated with a suitable fluid to remove or eliminate the starting material. This can be achieved by dissolution, etching, or other physical and / or chemical processes. Elimination of the starting material by incident radiation also appears conceivable. The starting material of the substrate, with its micro- or nanohollow structures, thus forms a "carrier and sacrificial structure" as a negative within the process chain, which exists only temporarily after fulfilling its function, namely the one described in step 2.) to provide a deposition platform with a suitable shaping surface for the (metallic) thin film deposited in the process chain (“metallization”), as it is no longer needed afterwards and would otherwise only cause problems in the further course of the process chain.

[0074] In the case of PVA as the starting material for the substrate, the removal of the "support and sacrificial structure" produced by 3D printing is carried out in a very environmentally friendly way using a warm water bath: The starting substrate, serving as the "support and sacrificial structure" (negative form), along with its micro- or nanohollow structures formed by the coating of the inner and / or outer surfaces (positive form), is placed in a heated water bath, which has a temperature of, for example, approximately 70°C. After one to two hours, the support material (negative form) has completely and environmentally dissolved, so that the remaining metal structure (positive form) can be removed.

[0075] In the case of glass as the starting material for the substrate, the removal of the "support and sacrificial structure"—i.e., the negative—created by focused femtosecond laser radiation and subsequent rinsing, is achieved using appropriate etching agents (hydrofluoric acid). These agents have the significant disadvantage of being highly hazardous to the health of the operating personnel, harmful to the immediate surroundings, and environmentally damaging during disposal. Furthermore, the etching time—that is, the time until all the starting material is completely etched away—can sometimes range from weeks to several months, which hinders the widespread industrial implementation of this method. Example 1:

[0076] A capillary structure made of PVA, or alternatively HIPS, with a length of 20 mm and a maximum outer diameter of 7.20 mm, containing approximately 40 channels, was used as the negative. This capillary structure was gas-tightly connected to a vacuum system using a two-component adhesive, according to the apparatus described in DE 198 52 722 Cl, and cleaned internally by simultaneously heating it to 450 K and passing through 1000 mbar of molecular oxygen. Subsequently, a constant base temperature of 400 K was maintained for one hour, followed by approximately 300 K. Bis-(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)palladium(II) was used as the precursor. The pressure gradient used was 10 -7 mbar against 10 -1mbar. The temperature, which is set locally, can remain unchanged throughout the coating process. However, this temperature can also be varied during the coating process. In particular, if the decomposition of the precursor material is accelerated autocatalytically by its decomposition product, the locally limited temperature can be reduced during the coating process. Such autocatalytic growth of the coating is observed, for example, when using bis-(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)palladium(II) as the precursor material, especially when hydrogen is used as the carrier gas.

[0077] Since PVA / HIPS is highly water-soluble, the support material for 3D printing was dissolved in warm water at approximately 320 K, releasing the resulting structure. This was then dried in a drying oven at approximately 400 K for 5 hours. 2. Example of implementation:

[0078] A capillary structure with twisted channels made of HIPS, with a length of 20 mm and a maximum outer diameter of 7.20 mm, was used as the negative. which contained approximately 4000 channels. This capillary structure was gas-tightly connected to a vacuum system using a two-component adhesive, according to the apparatus described in DE 198 52 722 CI, and cleaned internally by simultaneously heating it to 500 K and passing 1000 mbar of molecular oxygen through it.

[0079] A constant base temperature of 500 K was then maintained for ten hours to establish the structure. Osmium pentacarbonyl, Os(CO)s, was used as the precursor. The pressure gradient employed was 10 -9 mbar against 10 -4 mbar.

[0080] The temperature, which is set locally, can remain unchanged throughout the coating process. However, this temperature can also be varied during the coating process.

[0081] Since HIPS is readily soluble in d-limonene (orange terpenes), the support material for 3D printing was dissolved at approximately 400 K, releasing the resulting structure. This was then dried in a drying oven at approximately 400 K for 5 hours. Outlook

[0082] It remains to be seen whether this technology will be capable in the future of producing highly complex, preferably metallic or metal-containing micro- and nanostructures in such a way that they can be used, for example, in medical technology, such as stents for capillaries in the heart, kidneys, or other organs to prevent mini-infarctions. For this to be possible, the metallic materials used to manufacture the stents must be processable in this way, such as stainless steel or Nitinol, a biocompatible nickel-titanium alloy with a shape memory effect.

[0083] It may also be possible to fabricate drug-coated metal stents using this technology. Especially when coating the metal structures, the removal of the negative as a "support or sacrificial structure" must be carried out with particular care, as the coating must not be attacked by corrosive fluids. Therefore, water as a solvent, as in the case of PVA as a "support or sacrificial material," would be the first choice. Since stents can also be made of synthetic fibers, future research should investigate whether this technology is also suitable for the production of three-dimensional, non-metallic micro- and nanostructures. This could involve, for example, depositing a plasma polymer layer onto the surface of the inner surfaces of the micro- or nanohollow structure (in its simultaneous function as a "support and sacrificial structure") instead of metallization using a MOCVD process.Overall, the subject matter of this patent application, according to the invention, represents an attempt to meaningfully link and unite the two developments, directions, or trends of "micro- and nanotechnology" and "sustainability," which otherwise often run parallel to each other without any real connection, without truly interacting or exchanging ideas. Synergy effects are thus anticipated, since many sustainable technical solutions can be found in the field of micro- and nanotechnology. According to the invention, for the first time, components with micro- and nanodimensions based on materials with extremely high melting and boiling points, such as tungsten or osmium, can now be produced.with suitable aspect ratios and also in hollow form, it is now possible to manufacture in large quantities in a cost-optimized manner according to the invention, which is not possible according to the previous state of the art. Character description: Fig. 1: Algorithm of the process chain with the associated three steps or stages Fig. 2: Schematic drawing of the process chain a) Starting substrate 1 consisting of the starting material b) Substrate 1 with a micro- or nanohollow structure 2 after its creation, therefore only negative c) Metallized micro- or nanohollow structure 3 after successful metallization, therefore negative and positive d) After removal of the matrix or support structure (consisting of the starting material), only the desired micro- or nanostructure remains as positive 4. literature [dnat1] On the internet: < https: / / www.3dnatives.com / de / 3d-druck-materialienkunststoffe / >, accessed on October 30, 2023 [dnat2] On the internet: < https: / / www.3dnatives.com / de / pla-ein-leitfaden-zu-diesem-3d-druckmaterial-190820191 / #!>, accessed on October 30, 2023 [dnat3] On the internet: < https: / / www.3dnatives.com / de / selektives-lasersintern / >, accessed on October 30, 2023 [dnat4] On the internet: < https: / / www.3dnatives.com / de / fdm-oder-sla-151220171 / >, accessed on October 30, 2023 [dnat5] On the internet: < https: / / www.3dnatives.com / de / loesliche-filament-pva-im-3d-druck-250520221 / >, accessed on October 30, 2023 [dnat6] On the internet: < https: / / www.3dnatives.com / de / fdm-oder-sla-151220171 / >, accessed on October 30, 2023 [dnat7] On the internet: < https: / / www.3dnatives.com / de / top-12-verruckte-filamente-210320171 / >, accessed on October 30, 2023 [dnat8] Im Internet: < https: / / www.3dnatives.com / de / doppelextruder-3d-drucker-171020171 / >, recherchiert am 30. Oktober 2023 [Now1] Nowak, R; Metev, S.; Sepold, G.: Laser Chemical Etching of Metals in Liquids. In: Materials and Manufacturing Processes, Vol. 9, No. 4, 1994, Seiten 429 - 435 [Now2] Nowak, R.; Metev, S.; Sepold, G.: Nd:YAG laser-induced Wet Chemical Etching of Titanium and Stainless Steel. In: Sensors and Actuators A, Vol. 51, 1995, Seiten 41 - 45 [Now3] Nowak, R.; Metev, S.: Thermochemical Laser Etching of Stainless Steel and Titanium in Liquids. In: Appl. Phys. A 63, 1996, Seiten 133 - 138 [Schu1] Schulze Niehoff, H.; Vollertsen, F.: Versatile Micro Forming Press, Proc. 2nd ICNFT, BIAS-Verlag, Bremen (2007) 167-176 [Schu2] Schulze Niehoff, H.; Vollertsen, F.: Faster - more precise - more flexible realization of diametrically opposed requirements in a microforming machine, Journal for Economic Factory Operation, 7-8 (2008) [Voll1] Vollertsen, F; cow foot, B; Thomy, C; Friedrich, S; Maass, P; Zoch, H: F. Vollertsen, B. Kuhfuß, C. Thomy, S. Friedrich, P. Maaß, H.-W. Zoch (Eds.): Cold Metal Micro Forming. Research Report of the Collaborative Research Center “Micro Cold Forming” (SFB 747), Bremen, Germany Springer Nature Switzerland AG, Cham / CH (2020) [Voll2] Vollertsen, F.; Hu, Z.; Schulze Niehoff, H.; Theiler, C.; State of the art in micro forming and investigations in micro deep drawing, Journal of Materials Processing Technology, Vol. 151 (2004) 70-79 [wiki1] On the internet: < https: / / de.wikipedia.org / wiki / Fertigungsverfahren>, accessed on October 30, 2023 [wiki2] On the internet: < https: / / de.wikipedia.org / wiki / Umformen>, accessed on October 30, 2023 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 002 183 A1

[0010] DE 10 2018 009 670 A1

[0010] DE 10 2007 020 800 A1

[0011] DE 10 2007 049 929 B4

[0012] US 2015 / 0280228 A1

[0067] DE 198 52 722 [0076, 0078] Cited non-patent literature

[0000] https: / / www.3dnatives.com / de / 3d-druck-materialienkunststoffe / >

[0083] https: / / www.3dnatives.com / de / pla-ein-leitfaden-zu-diesem-3d-druckmaterial-190820191 / #!

[0083] https: / / www.3dnatives.com / de / selektives-lasersintern /

[0083] https: / / www.3dnatives.com / de / fdm-oder-sla-151220171 /

[0083] https: / / www.3dnatives.com / de / loesliche-filament-pva-im-3d-druck-250520221 /

[0083] https: / / www.3dnatives.com / de / top-12-verruckte-filamente-210320171 /

[0083] https: / / www.3dnatives.com / de / doppelextruder-3d-drucker-171020171 /

[0083] Nowak, R; Metev, S.; Sepold, G.: Laser Chemical Etching of Metals in Liquids. In: Materials and Manufacturing Processes, Vol. 9, No. 4, 1994, Seiten 429 - 435

[0083] Nowak, R.; Metev, S.; Sepold, G.: Nd:YAG laser-induced Wet Chemical Etching of Titanium and Stainless Steel. In: Sensors and Actuators A, Vol. 51, 1995, Seiten 41 - 45

[0083] Nowak, R.; Metev, S.: Thermochemical Laser Etching of Stainless Steel and Titanium in Liquids. In: Appl. Phys. A 63, 1996, Seiten 133 - 138

[0083] Schulze Niehoff, H.; Vollertsen, F.: Versatile Micro Forming Press, Proc. 2nd ICNFT, BIAS-Verlag, Bremen (2007) 167-176

[0083] Schulze Niehoff, H.; Vollertsen, F.: Faster - more precise - more flexible realization of diametrically opposed requirements in a microforming machine, Journal for Economic Factory Operation, 7-8 (2008

[0083] Vollertsen, F; cow foot, B; Thomy, C; Friedrich, S; Maass, P; Zoch, H: F. Vollertsen, B. Kuhfuß, C. Thomy, S. Friedrich, P. Maaß, H.-W. Zoch (Eds.): Cold Metal Micro Forming. Research Report of the Collaborative Research Center “Micro Cold Forming” (SFB 747), Bremen, Germany Springer Nature Switzerland AG, Cham / CH (2020

[0083] Vollertsen, F.; Hu, Z.; Schulze Niehoff, H.; Theiler, C.; State of the art in micro forming and investigations in micro deep drawing, Journal of Materials Processing Technology, Vol. 151 (2004) 70-79

[0083] https: / / de.wikipedia.org / wiki / Fertigungsverfahren

[0083] https: / / de.wikipedia.org / wiki / Umformen

[0083]

Claims

A method for producing three-dimensional, preferably metallic or metal-containing, ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial geometry, comprising the following three process steps: a. Production of a negative structure (negative) by generating micro- and / or nano(hollow) structures within the volume of a starting substrate (starting matrix), b. Production of a positive structure (positive) by coating the inner surfaces and optionally (partially) also the outer side surfaces (outer side surfaces) of the micro- and / or nano(hollow) structure preferably with a metal-containing, ceramic or polymeric coating, c.Release of the positive structure (Positive) from the negative structure (Negatives) by eliminating or removing the initial matrix material to release the three-dimensional, preferably metal-containing or ceramic or polymeric micro- and / or nanostructure, which is in the form of interconnected thin films covering the inner surfaces and, if applicable, also (partially) the outer surfaces of the micro- and / or nanostructure. A method for producing three-dimensional, preferably metal-containing, ceramic, or polymeric micro- and / or nano(hollow) structures with complex spatial geometry according to claim 1, wherein the negative structures (negative) are produced by means of a 3D printing process and / or an femtosecond laser-based processing process for generating micro- and / or nanostructures within the volume of a starting substrate (starting matrix), by guiding the focus of the femtosecond laser beam within the volume of the starting substrate along the geometric boundaries of the micro- and / or nano(hollow) structures to be produced in order to modify the material of the starting substrate in the femtosecond laser-exposed area in a physicochemical manner, so that it is soluble and washable in a suitable solvent.in order to subsequently wash out the modified area by applying a suitable solvent and thereby create the desired micro- and / or nano(hollow) structure. A method for producing three-dimensional, preferably metallic or metal-containing, or ceramic or polymeric micro- and / or nano (hollow) structures with complex spatial geometry according to claims 1 and / or 2, wherein the starting substrate (starting matrix) may consist of at least one of the following materials or combinations thereof:

1. Salts, preferably from molten salt technologies; 1.1 Inorganic salts such as preferably sodium nitrate, lithium nitrate, potassium nitrate, sodium chloride, and a mixture of 60% sodium nitrate and 40% potassium nitrate, alkali carbonates (Li₂CO₃ / K₂CO₃), or ternary mixtures of calcium nitrate and potassium (CN-K) from Yara, but also liquid salts; 1.2 Organic salts such as preferably those based on the alkali metals Li, Na, or K, or alkaline earth metals such as Ca or Mg; 2. Ionic liquids; 3. Polymers preferably water-soluble and / or organic solvent-soluble or corrosive polymers4.Combinations of 1.1 and / or 1.2 and / or 1. and / or 2. and / or 3. A method for producing three-dimensional, preferably metallic or metal-containing, or ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial geometry according to at least one of the preceding claims, wherein the coating of the inner surfaces and optionally (partially) the outer surfaces can be carried out by means of at least one of the following coating methods or combinations thereof: - generally CVD methods such as MOVCD, OMCVD, EOCVD, OECVD, PECVD, ECR-CVD - liquid methods such as CLD, preferably OMCLD and MOCVLD as well as OECLD and EOCLD - infiltration methods such as CVI, preferably OMCVD and MOCVD as well as OECVD and EOCVD - generally PVD methods, preferably also plasma-assisted methods - PLD methods - wet chemical impregnation methods A method for producing three-dimensional, preferably metallic or metal-containing, or ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial geometry according to at least one of the preceding claims, wherein the coating, wherein the starting precursors for the CVD or CLD process, preferably for the EOCVD or OECVD process, are selected from the group consisting of: • Chromium hexacarbonyl, • Tris(2,2,6,6-tetramethyl-3,5-heptanediumo)chromium(III), • Rhodium(III) acetylacetonate, • Copper(II) trifluoroacetylacetonate, • Copper(II) acetylacetonate, • Bis(hexafluoroacetylacetonato)copper(II), • Bis-(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)-• palladium(II),• tetracarbonylnickel,• nickelocene,• 2,2,6,6-tetramethyl-3,5-heptanedionatosilver(I),• Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)bismuth(III),• Tetraethyl lead,• Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)lead(II),• Uranium hexafluoride,• Uranium(III) iodide,• Uranium(IV) iodide,• Uranocene,• Uranium acetate,• Tungsten hexacarbonyl,• Dimethyl(hexafluoroacetylacetonato)gold,• Tetrakis(triphenylphosphine)platinum(0),• Bis(hexafluoroacetylacetonato)platinum(II),• Bis(acetylacetonato)platinum(II),• Dimethyl(1,5-cyclooctadiene)platinum(II),• Methylgold(I) compounds with phosphines and phosphites such as Methyl(triphenylphosphine)gold(I) or Methyl(trimethylphosphine)gold(I) as well as their derivatives,• bis-(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)lead(II),• tetraethyl orthosilicate (TEOS),• tetramethyl orthosilicate (TMOS),• tetrabutoxysilane,• triethoxyphenylsilane,• methyltripropoxysilane,• 1,2-bis(trimethoxysilyl)ethane,• 1,2-Bis(triethoxysilyl)ethane,• Phenethyltrimethoxysilane,• Isobutyltriethoxysilane,• Tris(2-methoxyethoxy)vinylsilane,• Octyltrimethoxysilane,• Phenyltriethoxysilane,• Octyltriethoxysilane,• Al(O-iso-C3H7),• Ti(O-iso-C3H7)4,• Zr(Ot-C4H9)4,• Zr(On-C4H9)4 and their• and their derivatives and mixtures., A method for producing three-dimensional, preferably metallic or metal-containing, or ceramic or polymeric, micro- and / or nano (hollow) structures with complex spatial geometry according to at least one of the preceding claims, wherein the inner or outer coating of the micro- and nanostructures according to the invention is applied by means of thin-film coatings and typically contains at least one element from the second to fifth main group or a subgroup, or a representative of the rare earth elements of the periodic table, and preferably contains an element selected from the group consisting of Ca, Mg, Al, Be, Ni, Pt, Cu, Pd, Ag, W, Re, Ir, Os, Au, Pb, Bi, and U, wherein the elements Ca, Mg, Al, Ni, Ag, Au, W, Os, Pd, Pt, Bi, and U are particularly preferred. In a further preferred embodiment, the element from the second to fifth main group of the periodic table is other than carbon. A method for producing three-dimensional, preferably metallic or metal-containing, or ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial geometry according to at least one of the preceding claims, wherein the coating process, in which the positive structure (positive) is released from the negative structure (negative), is carried out using at least one of the following methods or combinations thereof, depending on the starting material of the starting substrate (starting matrix): 1) Water bath at various temperatures, optionally with various surfactants (especially when water-soluble polymers are used as the starting substrate material); 2) Alcohol bath at various temperatures, optionally with various surfactants (especially when alcohol-soluble polymers are used as the starting substrate material); 3) Etching bath at various temperatures, optionally with various surfactants (especially when alcohol-soluble polymers are used as the starting substrate material).4) Acid bath at various temperatures, optionally with various surfactants (especially with water-soluble and / or corrosive polymers or salts as the starting substrate, where acids such as preferably hydrofluoric acid can be applied for a period of minutes to several days) 5) Alkali bath at various temperatures, optionally with various surfactants (especially with water-soluble and / or corrosive polymers or glasses as the starting substrate, where strong alkalis such as preferably sodium hydroxide or potassium hydroxide can be applied for a period of minutes to several days) 6) Ultrasonic bath at various temperatures, optionally with various surfactants 7) (Ion) sputtering device 8) Combinations of 1) - 7). Use of a method for producing three-dimensional, preferably metallic or metal-containing or ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial geometry according to at least one of the preceding claims. Use of a 3D printing device and / or an fs laser exposure device and / or a coating device preferably according to the MOCVD / OMCVD / EOCVD / OECVD, CVI process and / or a water, (aqueous) surfactant, alcohol and / or acid or alkali bath acid and / or (ion) sputtering device for carrying out a process for producing three-dimensional, preferably metallic micro- and / or nano(hollow) structures with complex spatial geometry according to at least one of the preceding claims. Three-dimensional metallic or metal-containing or ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial geometry produced according to a process according to at least one of the preceding claims (product-by-process) and their use for nanotechnological or microtechnological applications but also as a matrix for the production of nanoparticles. Use of three-dimensional metallic or metal-containing or ceramic or polymeric micro- and / or nano(hollow) structures with complex spatial, filigree geometry according to claim 10 for their use in nanotechnological or microtechnological applications but also as a matrix for the production of nanoparticles.

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